Determination of Hearing Threshold for Single Frequencies From the Acoustic Reflex

With preactivation, the threshold of stapedial reflex activity can be lowered by 20–30 dB. From these measures of the normal and reduced reflex threshold, an extrapolation may be performed down to the hearing threshold. Thus, the hearing threshold can be determined for every single frequency from 0.125 to 4 kHz if the reflex is elicitable up to 8 kHz.

Résumé

Graˇce à une pré-stimulation, le seuil du réflexe stapédien peut ětre réduit de 20 à 30 dB. Afin de déterminer le seuil d'audition, nous faisons une extrapolation à partir du seuil classique et du seuil réduit du réflexe. Il est ainsi possible de déterminer objectivement le seuil d'audition pour chaque fréquence entre 0.125 et 4 kHz, à condition que le réflexe stapédien puisse ětre obtenu jusqu'à 8 kHz.     

声场下噪声刺激对镫骨肌声反射幅值的影响

目的研究声场下不同强度的白噪声刺激对镫骨肌声反射幅值的影响。方法观察80名听力正常受试者在声场方式下给予不同强度（30、40、50和60dBSL）的白噪声刺激时,1、2和4kHz频率的声反射幅值的变化。结果受试者在给予白噪声刺激时声反射幅值较未给予白噪声刺激时明显降低（P〈0．01）,40dBSL强度的白噪声刺激时,声反射幅值降低最明显,2、4kHz的声反射幅值降低幅度较1kHz处明显（P〈0．01）,而2、4kHz处之间无明显差异（P〉0．05）。结论声场下白噪声刺激可致镫骨肌声反射幅值降低,临床上可以通过检测声场下白噪声刺激后镫骨肌声反射幅值的变化评估听觉传出神经的功能。     

The Acoustic Reflex Threshold: Not Predictive for Loudness Perception in Normally-hearing Listeners

The working hypothesis of an ongoing study is that the quick and reliable procedure of acoustic reflex threshold (ART) determination in conjunction with measurements of HTL may yield accurate estimates of loudness. The aim of this study was to investigate whether differences in loudness in normally-hearing subjects are reflected in the ARTs and to collect normal material with respect to pure-tone elicited ART and loudness categories. Categorical loudness scaling (CLS) and ART measurements were performed at frequencies of 0.5, 1, 2 and 4 kHz in 60 normally-hearing subjects (HTL<20 dB HL, 26 males, 34 females, aged 21–63 years) with no history or sequelae of middle ear disease. Subjects reporting disturbing tinnitus were excluded. The results show that the ART is not a predictor of individual loudness perception for normally-hearing subjects. Using a numerical scale (HTL = 0, ‘very soft’ = 5, ‘soft’ = 15, ‘OK’ =25, ‘loud’ = 35, ‘very loud’ =45 and ‘too loud’ =50) loudness for pure tones grows almost linearly at approximately 0.4 arbitrary loudness units per dB below the ‘loud’ category. Above the ‘loud’ category the slope is around 1 unit per dB. The median ART was 85 dB HL at frequencies of 0.5, 1, 2 and 4 kHz. No differences in loudness perception across frequencies were found.