The Role of the Medial Olivocochlear Reflex in Acceptable Noise Level in Adults.

BACKGROUND: The acceptable noise level (ANL) is a measurement used to quantify how much noise a person is willing to accept while listening to speech. ANL has been used to predict success with hearing aid use. However, physiological correlates of the ANL are poorly understood. One potential physiological correlate is the medial olivocochlear reflex (MOCR), which decreases the output of the cochlea and is thereby expected to increase noise tolerance. PURPOSE: This study investigates the relationship between contralateral activation of the MOCR and tolerance of background noise. RESEARCH DESIGN: This study recruited 22 young adult participants with normal hearing. ANL was measured using the Arizona Travelogue recording under headphones presented at the most comfortable level (MCL) with and without multitalker babble noise. The MOCR strength was evaluated in all participants by measuring the cochlear microphonic (CM) with and without 40 dB sound pressure level contralateral broadband noise (CBBN). DATA ANALYSIS: The CM observed in response to a 500-Hz tone was measured with and without CBBN, and changes in response to fast Fourier transform amplitude at 500 Hz were used as an indicator of the MOCR effect. The ANL was calculated by subtracting the maximum acceptable background noise level from the MCL. Participants were divided into two groups based on their ANL: low-ANL (ANL < 7 dB) and moderate-ANL (ANL ≥ 7 dB). An independent samples t-test was used to compare CM enhancement between low-ANL and moderate-ANL groups. Additionally, Pearson's correlation was used to investigate the relationship between the ANL and the MOCR effect on the CM. RESULTS: The results indicated that presentation of CBBN increased the CM amplitude, consistent with eliciting the MOCR. Participants in the low-ANL group had significantly larger CM enhancement than moderate-ANL participants. The results further revealed a significant correlation between the ANL and the MOCR effect on the CM. CONCLUSION: This study suggests that a stronger MOCR, as assessed using CM enhancement, is associated with greater noise tolerance. This research provides a possible objective measure to predict background tolerance in patients and adds to our understanding about the MOCR function in humans.

Comparing Loudness Tolerance and Acceptable Noise Level in Listeners With Hearing Loss.

The present study was a follow-up investigation to a previous study exploring the relationship between listeners' loudness tolerance and listeners' acceptable noise level among normally hearing adults. The present study compared the same two measures, but data were obtained from listeners with hearing loss; 12 adults with sensorineural hearing loss participated in a loudness tolerance measure using a scaling technique initially established for setting hearing aid output limits, in addition to an acceptable noise level measure. The acceptable noise level procedure used in this study quantified the listeners' acceptance of background noise while listening to speech. As with the research involving listeners with normal hearing, the Pearson correlation procedure indicated a lack of any statistically significant correlation between the two measures.

The relationship between the acceptance of noise and acoustic environments in young adults with normal hearing: a pilot study.

BACKGROUND: The acceptable noise level (ANL) indicates how much background noise a listener is willing to accept while listening to speech. The clinical impact and application of the ANL measure is as a predictor of hearing-aid use. The ANL may also correlate with the percentage of time spent in different listening environments (i.e., quiet, noisy, noisy with speech present, etc). Information retrieved from data logging could confirm this relationship. Data logging, using sound scene analysis, is a method of monitoring the different characteristics of the listening environments that a hearing-aid user experiences during a period. PURPOSE: The purpose of this study was to determine if the ANL procedure reflects the proportion of time a person spends in different acoustic environments. RESEARCH DESIGN: This was a descriptive quasi-experimental design to collect pilot data in which participants were asked to maintain their regular, daily activities while wearing a data-logging device. STUDY SAMPLE: After completing the ANL measurement, 29 normal-hearing listeners were provided a data-logging device and were instructed on its proper use. DATA COLLECTION/ANALYSIS: ANL measures were obtained along with the percentage of time participants spent in listening environments classified as quiet, speech-in-quiet, speech-in-noise, and noise via a data-logging device. RESULTS: An analysis of variance using a general linear model indicated that listeners with low ANL values spent more time in acoustic environments in which background noise was present than did those with high ANL values; the ANL data did not indicate differences in how much time listeners spent in environments of differing intensities. CONCLUSIONS: To some degree, the ANL is reflective of the acoustic environments and the amount of noise that the listener is willing to accept; data logging illustrates the acoustic environments in which the listener was present. Clinical implications include, but are not limited to, decisions in patient care regarding the need for additional counseling and/or the use of digital noise reduction and directional microphone technology.

Relationship between loudness tolerance and the acceptance of background noise for young adults with normal hearing.

This study investigated the relationship between listener loudness tolerance and listener acceptable noise level (ANL). Twenty-five normal hearing adults completed loudness tolerance and acceptable noise level measures. Loudness tolerance was measured using a scaling technique. The acceptable noise levels were calculated from a procedure designed to quantify a listener's willingness to accept background noise while listening to speech. Pearson correlation confirmed that loudness tolerance and acceptable noise levels are not related.

Comparing pure-, pulsed, and warbled tone thresholds in adults at 3000 and 6000 Hz.

PURPOSE: Pulsed and warbled tones are suitable substitutions for pure tones in hearing threshold measurement according to the 2005 American Speech-Language-Hearing Association guidelines. These guidelines also recommend measuring thresholds at 3000 and 6000 Hz. To date, there is no research directly supporting substitution of pulsed or warbled tones for pure tones at 3000 and 6000 Hz for listeners with normal hearing or with hearing loss. This study compared pure-, pulsed, and warbled tone thresholds at 3000 and 6000 Hz. METHOD: Forty-seven adults with normal hearing and 16 adults with sensorineural hearing loss participated in this study. Air-conduction thresholds were elicited with pure tones at octave intervals from 250 to 8000 Hz and with pure-, pulsed, and warbled tone stimuli at 3000 and 6000 Hz. RESULTS: Small mean differences in thresholds were obtained using each of the 3 stimulus types for both listeners with normal hearing and hearing loss. Some of the mean differences tested were found to be statistically significant. The differences were nevertheless small and in all cases within the clinically accepted 5-dB step size. CONCLUSION: Although substitutions did not violate the 5-dB step size, the slope of a listener's hearing loss may be a factor in the inaccuracy of measurement during the substitution of warbled tones for pure tones.

Qualitative research: implications for description and assessment.

As clinical speech-language pathologists seeking different ways to understand the complexity of communication within naturalistic and social contexts, we are progressively adapting the qualitative research methods of the social sciences for our assessment purposes. This article discusses some basic principles and practices discussed previously in this forum on qualitative research and demonstrates how they can be employed to provide effective and sufficient clinical communicative assessment.

The clinical analysis layer of transcription.

The clinical analysis layer of transcription is part of a 'toolkit' approach for detailed analysis of communication samples. This article provides a rationale for using the clinical analysis strategy and is supported by several examples of how a clinical analysis layer can add to the understanding of communication errors or other clinical areas of interest. The examples used in this paper are drawn from the areas of stuttering and aural rehabilitation and demonstrate the utility of this clinical analysis layer of transcription.