Measurement of sound

The measurement of sound involves the analysis of frequency, intensity, and temporal dimensions of acoustic signals. Each dimension of sound can be related directly to clinically observed phenomena. Frequency information, measured in Hz, can be extracted from pure-tone and complex stimuli. Intensity represents the physical energy of a signal and is described by using the decibel scale--a logarithmic scale of ratios. Temporal characteristics of sound include duration, phase, and repetition rate. In the analysis of human hearing sensitivity, the middle ear system and its impedance characteristics also must be considered. In this article, we have reviewed some major principles of sound and have presented a series of practical clinical applications. Such principles as these help to predict and explain frequency of laryngeal tones, middle ear mechanics, ear canal resonance, real-ear measurements of hearing aids, the Articulation Index, hearing loss, understanding of speech in quiet and in noise, and the relation between hearing and speech.     

Azimuthal sound source localization of various sound stimuli under different conditions

AimTo evaluate azimuthal sound-source localization performance under different conditions, with a view to optimizing a routine sound localization protocol.Material and methodTwo groups of healthy, normal-hearing subjects were tested identically, except that one had to keep their head still while the other was allowed to turn it. Sound localization was tested without and then with a right ear plug (acute auditory asymmetry) for each of the following sound stimuli: pulsed narrow-band centered on 250 Hz, continuous narrowband centered on 2000 Hz, 4000 Hz and 8000 Hz, continuous 4000 Hz warble, pulsed white noise, and word (“lac” (lake)). Root mean square error was used to calculate sound-source localization accuracy.ResultsWith fixed head, localization was significantly disturbed by the earplug for all stimuli (P < 0.05). The most discriminating stimulus was continuous 4000 Hz narrow-band: area under the ROC curve (AUC), 0.99 [95% CI, 0.95–1.01] for screening and 0.85 [0.82–0.89] for diagnosis. With mobile head, localization was significantly better than with fixed head for 4000 and 8000 Hz stimuli (P < 0.05). The most discriminating stimulus was continuous 2000 Hz narrow-band: AUC, 0.90 [0.83–0.97] for screening and 0.75 [0.71–0.79] for diagnosis. In both conditions, pulsed noise (250 Hz narrow-band, white noise or word) was less difficult to localize than continuous noise.ConclusionThe test was more sensitive with the head immobile. Continuous narrow-band stimulation centered on 4000 Hz most effectively explored interaural level difference. Pulsed narrow-band stimulation centered on 250 Hz most effectively explored interaural time difference. Testing with mobile head, closer to real-life conditions, was most effective with continuous narrow-band stimulation centered on 2000 Hz.     

声音是怎么回事?

声音让我们的世界充满了生机，声音中包含的信息构成了我们学习的主要内容。那么声音是如何产生?如何传播?又如何引起我们注意的呢?     

Spatial discrimination of sound sources in the horizontal plane following an adapter sound

The effect of a preceding (adapter) sound on the spatial discrimination of two subsequent, successively presented (target) sounds was tested in the horizontal plane. The adapter and the first target were located in front of the subject or 30 degrees to the right of the midline; both sounds were presented either at the same location or at different locations. The second target was located to the right or the left of the first. Sound spectra of the 3-s adapter and the 100-ms targets were either high (4.5-18 kHz) or low (1-4 kHz) in frequency. Fifteen subjects judged the position of the second target relative to the first in a two-alternative forced-choice paradigm. In comparison with a no-adapter control condition, in which no sound preceded, discrimination performance was increased when adapter and first target were presented at the same location and when both sounds consisted of the same frequency spectrum. No improvement occurred when adapter and targets differed in location or frequency. The results are consistent with previous results on post-adaptation discrimination of interaural time differences. Possibly, spatial adaptation of the underlying mechanisms of auditory localization may explain the discrimination aftereffect.     

Sequential sound therapy in tinnitus

Sequential sound therapy, which uses wide-band white noise distinguished by some unique characteristics, is applied in the treatment of tinnitus. The methodology is described, as are the differences from and similarities to tinnitus retraining therapy. We have performed sequential sound therapy in 26 patients from 2002 through part of 2003. Thirty-eight generators of sounds were adapted for use in this therapy and, of these, 34 incorporated an earphone. The results of sequential sound therapy in our 26 patients were compared with the results of tinnitus retraining therapy in 15 patients treated during the years 2000 and 2001. Satisfactory results obtained with sequential sound therapy totaled 100%, whereas only 33% of subjects treated with tinnitus retraining therapy obtained satisfactory results. In 6 patients who received sequential sound therapy, tinnitus disappeared altogether. In addition, no patient receiving sequential sound therapy has left the treatment protocol, whereas 53% of patients receiving tinnitus retraining therapy abandoned the treatment protocol.     

Sequential sound therapy in tinnitus

The sequential sound therapy is a treatment for tinnitus with white noise that has some own characteristics. We describe the methodology, as well as their differences and similarities with the Tinnitus Retraining Therapy. The sequential sound therapy has been carried out to seventeen patients assisted during the year 2002. 26 generators of sound were adapted, of them, 22 had incorporated an earphone. The results of the sequential sound therapy were compared with those of the Tinnitus Retraining Therapy in 15 patients assisted during 2000 and 2001. The percentage of satisfactory results obtained with sequential sound therapy has been a 100%, while the therapy with sounds of the Tinnitus Retraining Therapy obtained a 33%. With the sequential sound therapy 6 patients had no further tinnitus. With the sequential sound therapy no patients has abandoned the treatment. With the treatment with sounds of the Tinnitus Retraining Therapy of the patients did give up the therapy 53%.     

听觉耐受下降与耳鸣

听觉耐受下降(decreased sound tolerance)是指对声音的容忍度降低,或指对声音的敏感性增强,包括听觉过敏,厌声症,恐声症〔1〕。耳鸣是指在周围环境中无相应声源或电刺激存在的情况下,患者自觉耳内或颅内有声音的一种主观感觉;常伴或     

Role of the dog's auditory cortex in discrimination of sound signals simulating sound source movement

The ability of seven dogs to discriminate signal simulating sound source movement was studied using the avoidance technique. It was found that dogs can differentiate moving and stationary sound sources, and also discern the direction of the sound source movement. In addition, this study has defined the limits of the conditions under which sound source movement perception occurs. In each dog, unilateral ablation of the auditory cortex was followed by a localization deficit on the side contralateral to the ablation. Bilateral cortical lesions led to complete absence of the ability to discriminate source movement, simulated by changing stimulus interaural time differences. However, the dogs' ability to discriminate the movement after unilateral ablation by detecting interaural intensity differences was preserved, although their discriminative ability was lower than that of intact dogs.     

Preattentive memory-based comparison of sound intensity

Changes in the intensity of repeated, ignored sounds elicit the mismatch negativity (MMN) brain response which reflects preattentive detection of the change. It is generally assumed that the MMN in response to intensity changes reflects a memory-based comparison mechanism rather than being due to differential states of refractoriness of intensity-specific cortical neurons. In the present study, an experimental protocol consisting of 4 oddball blocks and 1 control block was used in order to separate memory-comparison-related effects from refractoriness-related ones. This design allowed an assessment of intensity MMN using physically identical stimuli with equal probability of occurrence in separate blocks, while avoiding contamination by refractoriness. Results were consistent with an MMN in response to intensity change that reflects genuine memory-based comparison.