Masked threshold changes associated with angular separation of noise and signal sources

Threshold changes associated with separating a signal source and a masking white noise source from 0 degree to 90 degrees were determined for 0.5, 1 and 8 kHz pure tones and click trains. No changes occurred for the 0.5 and 1 kHz pure tones. Masked thresholds of 8 kHz pure tones and click trains decreased linearly by 9 and 13 dB respectively as angular separation was moved from 0 degree to 90 degrees. Changes in click train stimuli masked thresholds did not change significantly when the ear directed toward the masking source was occluded (11 dB drop at 90 degrees). The absence of changes at low frequencies and the similarity in magnitude of the changes in signals containing high frequency components with the responses to the monaural click trains, suggests that the threshold changes can be attributed to a head shadow effect. The casting of a sound shadow effectively lowers the noise level on the shielded side. These findings question the importance of cross-correlation techniques when detecting signals in noise.     

Responses of chopper units in the ventral cochlear nucleus of the anaesthetised guinea pig to clicks-in-noise and click trains

Auditory brainstem responses (ABRs) have been measured with clicks, clicks masked by noise, click trains and pseudorandom maximum length sequences (MLS) of clicks. To investigate the neuronal populations contributing to the ABR under these stimulation conditions, we measured the extracellular responses of ventral cochlear nucleus (VCN) units in the urethane-anaesthetised guinea pig. We studied 23 chopper, 7 primary-like and 7 onset units. This report focuses on the responses from chopper units. The probability of discharge for chopper units increased with increasing click level reaching nearly 100% in many units, over a range of about 20–30 dB. Following each response to a click there was a 5–10 ms suppression of the spontaneous or noise evoked activity. As the level of the noise was increased over a range of 20–30 dB, the response to the clicks gradually decreased leading to a complete abolition of the click response at high noise levels. In a few units, low level noise produced a facilitation of the response to single clicks. In response to constant level equally spaced click trains, discharge probability increased with increasing minimum pulse interval (MPI), approaching 100% for MPIs of 4–8 ms in some units. The recovery afforded by the gaps in the MLS train often resulted in higher discharge probability for MLS than click trains with the same MPI, while response probabilities for MLS and click trains were similar when compared at equivalent average click rates. At short MPIs (0.5 and 1.0 ms), peri stimulus time histograms in response to click trains resembled those to best frequency (BF) tones and noisebursts, with chopping peaks unrelated to unit BF. VCN units show highly synchronised and reliable responses to click trains, MLS trains and clicks masked by noise. The decrease in discharge rate and increase in latency of chopper units with decreasing click level, increasing click rate and increasing masker level parallel the peak amplitude and latency changes observed in the auditory brainstem response.     

Dead regions and noisiness of pure tones

Some hearing-impaired subjects report pure tones as sounding highly distorted and noise-like. We assessed whether such reports indicate that the tone frequency falls inside a dead region (DR). Nine hearing-impaired and four normally hearing subjects rated pure tones on a scale from 1 to 7, where 1 indicates clear tone and 7 indicates noise. A white noise was presented as a reference for a sound that should be rated as 7. Stimuli covered the whole audible range of frequencies and levels. The noisiness ratings were, on average, higher for hearing-impaired subjects than for normally hearing subjects. For the former, the ratings were not markedly different for tones with frequencies just outside or inside a DR. However, ratings always exceeded 3 for tones falling more than 1.5 octaves inside a DR. The results indicate that judgement of a tone as sounding noise-like does not reliably indicate that the tone frequency falls in a DR. Both normally hearing and hearing-impaired subjects rated 0.125?kHz and 12?kHz tones as somewhat noise-like, independently of the existence of a DR.     

Dead regions and noisiness of pure tones

Some hearing-impaired subjects report pure tones as sounding highly distorted and noise-like. We assessed whether such reports indicate that the tone frequency falls inside a dead region (DR). Nine hearing-impaired and four normally hearing subjects rated pure tones on a scale from 1 to 7, where 1 indicates clear tone and 7 indicates noise. A white noise was presented as a reference for a sound that should be rated as 7. Stimuli covered the whole audible range of frequencies and levels. The noisiness ratings were, on average, higher for hearing-impaired subjects than for normally hearing subjects. For the former, the ratings were not markedly different for tones with frequencies just outside or inside a DR. However, ratings always exceeded 3 for tones falling more than 1.5 octaves inside a DR. The results indicate that judgement of a tone as sounding noise-like does not reliably indicate that the tone frequency falls in a DR. Both normally hearing and hearing-impaired subjects rated 0.125 kHz and 12 kHz tones as somewhat noise-like, independently of the existence of a DR.     

detection of early noise-induced hearing impairment in pilots

Objective To detect early signs of noise-induced hearing loss(NIHL) in military pilots without hearing complaints. Methods Pure tone audiometry and acoustic reflex thresholds were tested in 36 military pilots (72 ears) with noise exposure history but no complaints of hearing loss. Conventional test frequencies (0.25-8 kHz) and extended high frequencies (EHF, 10 and 12.5 kHz) were included in audiometry. White noise and pure tones at 0.5, 1, 2, and 4 kHz were used for acoustic reflex tests. Twenty normal hearing subjects(40 ears) with no exposure to occupational noise were used as controls. Results Pure tone thresholds at all conventional frequencies and at EHFs were elevated in the pilots, with the maximum shift at 4 kHz, compared with controls (p < 0.01 ). The pilots also showed elevated ART to white noise and decreased differentials between white noise and pure tone ARTs (p< 0.01 ). Conclusion Early signs of NIHL are present in some symptom-free military pilots. High frequency hearing threshold shift, elevated white noise ART and decreased differential between white noise and pure tone ARTs may be objective indicators of early NIHL.     

Assessment of the medial olivocochlear efferent system in children. pure tone 1.0 kHz and 2.0 kHz suppressive effects on transient evoked otoacoustic emission

The role of medial efferent system in regulating outer hair cell function has been studied by many investigators. Usually narrow band noise or white noise as contralateral stimulation (CS) suppressors have been used and changes in OAE amplitudes estimated. Thirty children aged 6-15 years (mean 12.5 +/- 4.7), without any changes in tonal and impedance audiometry and with negative history regarding otiatric diseases were examined. Transient evoked otoacoustic emissions (TEOAE) were recorded using ILO 92 Otodynamics Analyser. CS was performed using 1.0 kHz and 2.0 kHz continuous pure tones of 30 dB SL or 50 dB SL. Effects of CS on TEOAE evoked by click of 80, 70 and 60 dB SPL were investigated. TEOAE analysis included assessment of TEOAE amplitude of half octave frequency bandwidth (HOFBW-1.0; HOFBW-1.5; HOFBW-2.0; HOFBW-3.0 and HOFBW-4.0 kHz) and 0.8 kHz frequency bandwidth (0.8-FBW) amplitudes centred at 1.0; 2.0; 3.0; 4.0 and 5.0 kHz. TEOAE amplitude recorded for stimuli 80, 70 and 60 dB SPL without CS decreased: mean values respectively 6.1 +/- 4.2; 5.4 +/- 4.5 and 3.3 dB SPL +/- 4.3. CS effect on TEOAE was observed for all CS options, however, larger suppressive effect was recorded on TEOAE elicited by 70 dB SPL stimulus using 1 kHz/50 dB SL tone as a suppressor and on TEOAE elicited by 60 dB SPL stimulus using 2 kHz/50 dB SL tone as a suppressor. HOFBW and 0.8-FBW analyses showed the association between the frequency/intensity of the suppressors and decreasing of amplitudes of adequate frequency bands. It is concluded that the described method of investigating of the medial olivocochlear efferent system seems to be sensitive and confirms frequency-dependent suppressive effect on OAE.     

Enhancement and suppression in the auditory midbrain nucleus (MLD) of the pigeon.

Auditory evoked potentials (AEPs) and spike responses were recorded from the same recording site in the nucleus mesencephalicus lateralis pars dorsalis (MLD) in pigeons with a tungsten microelectrode. Depending on the recording sites within the MLD, enhancement and suppression of the AEPs in response to clicks were observed at particular frequencies of a background continuous pure tone. Post stimulus time histograms (PSTs) of the spike responses, if available in such cases, were recorded from the same position by the same electrode. Suppression of the AEPs always occurred but enhancement occurred in only 21% of the trials. The frequencies of tone bursts that caused maximum AEP were vaguely related to the frequencies of continuous pure tones that elicited maximum suppression of the AEPs in response to clicks. However, enhancement was produced by a continuous pure tone of approximately 1.5 kHz, independent of the frequencies of tone bursts that produced maximum AEPs. Most of the PSTs in such instances showed parallel relations between the spike responses and the amplitudes of the AEPs. The nature of the enhancement and suppression of the click evoked AEPs during continuous pure tones was clearly different from those in recordings from the nucleus magnocellularis, nucleus angularis and Field L in respect to the probability of occurrence of enhancement and suppression.     

Auditory nerve spatial encoding of high-frequency pure tones: population response profiles derived from d' measure associated with nearby places along the cochlea

We examined a measure of discriminability in auditory nerve (AN) population responses that may underlie behavioral frequency discrimination of high-frequency pure tones in the cat. Population responses of high- (greater than = 15 spikes/s) and low- (less than 15 spikes/s) spontaneous rate (SR) AN fibers in unanesthetized decerebrate cats to 5 kHz pure tones were measured in the form of mean, mu, and standard deviation, sigma, of spike counts for 0.2 s tone bursts. The AN responses were analyzed in terms of a d'e(x, delta x) associated with adjoining cochlear places as defined in the manner of signal detection theory. We also examined sigma d'e(x, delta x), a spatial summation of the discriminability measure. The major findings are: (1) the d'e(x, delta x) function conveys information about 5 kHz pure tone frequency over a region of +/- 0.5 to 1.0 octave, or +/- 1.67 to 3.33 mm, around the characteristic place (CP), with the region being narrower at lower stimulus levels; (2) at 30 dB SPL, the integrated d'e(x, delta x) discriminability scores are similar for the apical and basal regions surrounding the CP whereas, at 70 dB SPL, the scores are higher for the apical region than for the basal region; and (3) at 50 and 70 dB SPL, the integrated d'e(x, delta x) discriminability scores of low-SR fibers were higher than those of high-SR fibers although, at 30 dB SPL, the latter were higher than the former. By using the cat cochlear frequency-place relationship and the inner hair cell (IHC) spacing, we interpret that the cat's frequency difference limen, delta f/f = 0.0088 at 4 kHz [Elliott et al., 1960, J. Acoust. Soc. Am. 32, 380-384], corresponds to a shift of cochlear excitation profile by 4.5 IHCs. From the present analysis of AN responses, we conclude that, for high-frequency pure tones, the d'e(x, delta x) code, an example of rate-place code, of frequency provides sufficient information to support the cat's behavioral frequency discrimination.     

Calculating the Hearing Threshold from the Stapedius Reflex Threshold for Different Sound Stimuli

The acoustic stapedius reflex depends not only on stimulus intensity, but also on stimulus frequency, as far as reflex threshold, amplitude of response and reflex decay are concerned. The stapedius reflex threshold (SRT) for wide-band noise has been proved lower than that for pure tones. Our own investigations dealt with the relation between the SRTs for pure tones, white noise, and a 24-tone mixture (one single tone at every critical band width) in normal-hearing persons and patients suffering from sensorineural hearing loss

In normal hearing, the SRT for pure tones was measures at 70-85 dB (73-105 dB SPL) above the normal-hearing threshold in a free sound-field, the SRT for white noise (average) at 46.5 dB (68.5 dB SPL) and the SRT for the 24-tone mixture at 47.0 dB (67.2 dB SPL). In 125 patients (223 ears), the difference level between the mean SRT for tones of 0.5-4 kHz and the SRT for white noise (dl 2) was correlated with the difference level between the mean SRT for tones of 0.5-4 kHz and the mean hearing threshold for tones of 0.5-4 kHz (dl 1). The functions were found to be roughly linear: dl 2 = dl 1/2.5 and dl 1 = 2.5 dl 2. Validity: 73% ～ 10 dB; 17% ～ 15 dB, and 10% ～ 20 dB. Since the dB-value of the mean SRT for pure tones of 0.5-4 kHz can be read from the audiogram, it is possible to calculate the mean hearing threshold for 0.5-4 kHz from dl 2 with equal validity: mean hearing threshold 0.5-4 kHz = SRT tones -2.5 dl 2

In cases of falling threshold curves the results become less exact and in addition to the SRT for white noise and pure tones, the SRT for two tone-mixtures was determined, namely for one low-pass noise consisting of 12 sine waves of 100-1 600 Hz, and for one high-pass noise consisting of 12 sine waves of 1.8-13.5 kHz. In normal hearing, the dl 2 for the low-pass noise is ～ 15 dB and for the high-pass noise ～ 20 dB (3:4). In falling audiograms, the dl 2 for the high-pass noise was found to be equal or lower than that for the low-pass noise. Investigations in sleeping children indicated that these relations were practically unchanged

A correlation of the free-field findings with the loudness calculated by Zwicker's procedure showed that the triggering of the stapedius reflex by wide-band sounds is due to the centrally summated loudness and not the SPL     

Nonlinear explanation for bone-conducted ultrasonic hearing

Human listeners can perceive speech from a voice-modulated ultrasonic carrier presented via a bone-conduction stimulator. This study explored the psychoacoustic characteristics and underlying mechanisms of ultrasonic hearing by measuring difference limens for frequency (DLF) for pure tones modulated onto ultrasonic carriers. Human subjects were presented with two pulsed tones and asked to judge whether the first or the second had the higher pitch. When amplitude modulation was based on a double side-band transmitted carrier, the DLFs were as small as those from the air-conducted pure tones at 0.25-4 kHz. Ultrasounds yielded larger DLFs for tones with low (0.125 kHz) and high (6-8 kHz) frequencies. Results were essentially identical between the two types of carriers, sine wave (30 kHz) and bandpass noise (30+/-4 kHz), despite the different bandwidths in the ultrasonic range. When amplitude modulation was based on a double side-band suppressed carrier, DLFs corresponded to those from tones with double frequencies. These results suggest nonlinear conduction that demodulates audible signals from ultrasounds and provides inputs to the cochlea.     

Twenty-stimulus train for rapid acquisition of auditory brainstem responses in humans

This study addressed the clinical need to obtain frequency-specific auditory brainstem responses (ABRs) more rapidly than is currently possible. ABRs were obtained from 20 subjects using two different methods: a conventional method with tone bursts presented singly and a multiple-stimulus method using a train of 20 tone bursts. For both methods, tone bursts were presented at frequencies 1, 2, 4, and 8 kHz, shaped with a Blackman-Harris window and having intensity levels up to 105 dB peak equivalent sound pressure level (peSPL). The single tone bursts were presented at a 17.2/sec repetition rate. The 20 tone-burst train used the four frequencies at five intensities each and a repetition rate of 3.7/sec (separations between tone bursts of 9-12 msec, with 77 msec off-time between trains). Mean latencies and mean amplitudes for wave V were compared using t-tests for each of 12 conditions (four frequencies, each at the three highest output levels). For latency, only one comparison was significantly different (2 kHz, 77 dB peSPL). Similarly, only one comparison was significant for amplitude (2 kHz, 97 dB peSPL). There was, however, a trend for the tone bursts presented in trains to have longer latencies and reduced amplitudes compared to the respective responses for the single tone-burst condition. These results indicate the presence of some response adaptation when tone bursts are presented in a train. The use of a properly designed stimulus train can result in a significant time savings for obtaining frequency-specific ABRs as compared with single tone-burst presentations.     

不同分娩方式新生儿听性行为反应分析

目的 探讨非听力因素对新生儿听性行为反应的影响,为提高新生儿行为测听法的灵敏度和特异性提供参考。方法 １０２名正常新生儿按分娩方式为顺产组４２例,剖宫产组６０例,经瞬态诱发性耳声发射（ｔｒａｎｓｉｅｎｔ ｅｖｏｋｅｄ ｏｔｏａｃｕｓｔｉｃｅｍｉｓｓｉｏｎ,ＴＥＯＡＥ）测试;后声场给声,刺激声分别为３ｋＨｚ纯音、高频窄带噪声及白噪声,声强为９０ｄＢＳＰＬ分析恒定强度下眼睑反应、头颈反应、面部反应、     

Detection of Tones and Their Modification by Noise in Nonhuman Primates

A fundamental function of the auditory system is to detect important sounds in the presence of other competing environmental sounds. This paper describes behavioral performance in a tone detection task by nonhuman primates (Macaca mulatta) and the modification of the performance by continuous background noise and by sinusoidally amplitude modulating signals or noise. Two monkeys were trained to report detection of tones in a reaction time Go/No-Go task using the method of constant stimuli. The tones spanned a wide range of frequencies and sound levels, and were presented alone or in continuous broadband noise (40 kHz bandwidth). Signal detection theoretic analysis revealed that thresholds to tones were lowest between 8 and 16 kHz, and were higher outside this range. At each frequency, reaction times decreased with increases in tone sound pressure level. The slope of this relationship was higher at frequencies below 1 kHz and was lower for higher frequencies. In continuous broadband noise, tone thresholds increased at the rate of 1 dB/dB of noise for frequencies above 1 kHz. Noise did not change either the reaction times for a given tone sound pressure level or the slopes of the reaction time vs. tone level relationship. Amplitude modulation of tones resulted in reduced threshold for nearly all the frequencies tested. Amplitude modulation of the tone caused thresholds for detection in continuous broadband noise to be changed by smaller amounts relative to the detection of steady-state tones in noise. Amplitude modulation of background noise resulted in reduction of detection thresholds of steady-state tones by an average of 11 dB relative to thresholds in steady-state noise of equivalent mean amplitude. In all cases, the slopes of the reaction time vs. sound level relationship were not modified. These results show that macaques have hearing functions similar to those measured in humans. These studies form the basis for ongoing studies of neural mechanisms of hearing in noisy backgrounds.     

Local auditory evoked potentials and effects of pure tones on click evoked potentials in the pigeon

Local auditory evoked potentials (AEPs) in the pigeon were recorded from the nucleus magnocellularis (NM), nucleus angularis (NA) and Field L with tungsten microelectrodes. In the NM and NA, AEPs in response to clicks were always suppressed by application of continuous pure tones at specific frequencies as is usual for simultaneous masking. In the NA, frequencies of continuous pure tones which produced maximum suppression and frequencies of tone bursts which elicited maximum response both centered around 0.8 kHz. The NM tended to respond similarly. In Field L, however, amplitudes of the AEPs to clicks were suppressed, enhanced, both suppressed and enhanced, or unaffected by presentation of continuous pure tones at specific frequencies. The frequencies of tone bursts which caused maximum AEP were vaguely related to the frequencies of continuous pure tones which elicited maximum suppression of the AEPs to clicks. On the other hand, enhancement was produced by 1-2 kHz continuous pure tones independent of the frequency of tone bursts that produced maximum AEP. It was concluded that enhancement, suppression and lack of effect in Field L were due to some central neural mechanism.     

Otoacoustic emission examinations in soldiers before and after shooting

Firearms are a common source of impulse noise that may potentially damage hearing organ. The purpose of this study was evaluation of the click evoked otoacoustic emission (TEOAE) and distortion-product otoacoustic emission (DPOAE) before and after shooting and comparison with conventional pure tone audiometry. Standard pure tone audiometry, tympanometry, TEOAE and DPOAE were made before and 10-15 minutes after shooting. Ten male soldiers (20 ears) were exposed to impulse noise from automatic gunfire (15 single rounds of live ammunition). They did not use any earplugs. The reduction amplitude of the TEOAE after shooting was found especially for the frequency 3,4 kHz for the right ear and 1 and 2 kHz for the left ear. The DPOAE greatest reduction concerned frequency 2,5 and 4 kHz for the left ear. All our shooters were right-handed and probably the asymmetrical effect resulted from the shooting posture. Any differences existing between the audiometric threshold before and after shooting were not noticed. Clinical experience with OAE indicates that it may play a role as a screening method for the soldiers exposed to noise and as a tool for monitoring early changes in cochlea. Emissions seem to be more sensitive for monitoring early cochlear changes after shooting than pure tone audiometry.     

Steady-state auditory evoked potentials to amplitude-modulated tones in hearing-impaired subjects

Evoked potentials to sinusoidal amplitude-modulated tones have been described in normally hearing adults. Our aim was to test the use of this response to estimate pure tone threshold in adults with a sensorineural hearing loss. Patients with symmetrical pure tone audiograms with near-normal responses in the lower frequencies but with a hearing loss of greater than 65 dB HL at 8 kHz were tested. The stimulus carrier frequency was 1, 2, 4 and 8 kHz and this was modulated at a frequency of 40 kHz to a depth of 85%. The resulting EEG response is a sine wave of the same frequency as the modulation frequency. Threshold is determined when the sine wave disappears. Twenty-two patients were tested. None showed a response to the high frequencies. At the lower frequencies 18 patients showed clear responses and the threshold was 16 to 27 dB above the psychoacoustical threshold. The remaining four cases showed responses at the lower frequencies but only at higher threshold levels. These evoked potentials may provide a rapid method to assess hearing in those subjects unable to provide a reliable volitional response.     

Equivalence and test–retest reproducibility of conventional and extended-high-frequency audiometric thresholds obtained using pure-tone and narrow-band-noise stimuli

Objectives: Extended high-frequency (EHF) audiometry is useful for evaluating ototoxic exposures and may relate to speech recognition, localisation and hearing aid benefit. There is a need to determine whether common clinical practice for EHF audiometry using tone and noise stimuli is reliable. We evaluated equivalence and compared test-retest (TRT) reproducibility for audiometric thresholds obtained using pure tones and narrowband noise (NBN) from 0.25 to 16?kHz. Design: Thresholds and test-retest reproducibility for stimuli in the conventional (0.25–6?kHz) and EHF (8–16?kHz) frequency ranges were compared in a repeated-measures design. Study sample: A total of 70 ears of adults with normal hearing. Results: Thresholds obtained using NBN were significantly lower than thresholds obtained using pure tones from 0.5 to 16?kHz, but not 0.25?kHz. Good TRT reproducibility (within 2?dB) was observed for both stimuli at all frequencies. Responses at the lower limit of the presentation range for NBN centred at 14 and 16?kHz suggest unreliability for NBN as a threshold stimulus at these frequencies. Conclusion: Thresholds in the conventional and EHF ranges showed good test-retest reproducibility, but differed between stimulus types. Care should be taken when comparing pure-tone thresholds with NBN thresholds especially at these frequencies.     

Predicting pure-tone thresholds with dichotic multiple frequency auditory steady state responses

The accuracy of dichotic multiple frequency auditory steady state in predicting pure-tone thresholds at 0.5, 1, 2, and 4.0 kHz compared to an ABR protocol (click and tone burst at 0.5 kHz) were explored in a group of 25 hearing-impaired subjects across the degree and configuration spectrum. Mean steady state thresholds were within 14, 18, 15, and 14 dB of the pure tones at 0.5, 1, 2, and 4 kHz, compared to the tone-burst ABR at 0.5 kHz pure-tone difference of 24 dB, and a click-evoked pure-tone (2-4 kHz) difference of 9 dB. Recording time for the steady state protocol was 28 minutes (+/- 11) compared to 24 minutes (+/- 9) of the ABR protocol. Degree of loss had a significant effect on steady state; configuration of hearing loss had a limited effect. Mf ASSR predicted thresholds with relative accuracy although some configurations showed discrepancies for low-frequency estimates.     

畸变产物耳声发射在军事噪声致爆震性聋早期监测中的作用

目的探讨畸变产物耳声发射(DPOAE)在军事噪声致爆震性聋早期监测中的作用。方法将听力正常的炮兵某部男性官兵88例(176耳)随机分成两组,每组44例(88耳),实验组参加火炮实弹射击训练,对照组未参加火炮实弹射击训练。对照组及实验组训练前后进行纯音测听及DPOAE测试,对两组结果进行比较分析。结果实验组训练后80耳中耳传导功能无障碍,其中13耳纯音听阈示感音神经性听力损失,DPOAE检查亦异常;67耳纯音听阈正常,其中15耳DPOAE幅值在4kHz处降低。与训练前、对照组比较,实验组训练后2、4及8kHz纯音听阈升高(P<0.05或P<0.01),以4kHz处升高最为明显;实验组训练后2、3、4、6及8kHzDPOAE幅值降低(P<0.05或P<0.01),其中以4kHz处降低最为明显。结论畸变产物耳声发射在军事噪声致爆震性聋早期监测中有一定应用价值,可对其防护、诊断和治疗提供指导和帮助。     

Extended high‐frequency audiometry in patients with acoustic trauma

Objectives: The aim of this study was to examine extended high‐frequency (EHF) hearing in patients with acoustic trauma. Design: A prospective, case–control study in a group of soldiers with acoustic trauma caused by shooting practice during basic training. Setting: Tertiary referral centre. Participants: A total of 39 young soldiers hospitalized for hearing loss and tinnitus following exposure to weapon impulse noise were studied. Conventional audiometry in the frequency range 0.25–8 kHz and EHF audiometry in the frequency range 9–20 kHz were performed, both on admittance and before discharge. Thirty healthy recruits of similar age and sex were used as controls. Main outcome measures: Pure‐tone threshold changes documented by conventional and EHF audiometry. Results: The most significant differences in pure‐tone thresholds on initial testing were found in the frequency range 0.25–11.2 kHz, and especially in the 4–8 kHz region. Reduction in thresholds across most frequencies was observed after treatment, although recovery was partial in most cases. Conclusions: The EHF audiometry adds no significant additional information to conventional pure‐tone audiometry in assessing and monitoring noise‐induced hearing loss.