The Impact of Transducer Selection on the Acceptable Noise Level.

PURPOSE: The aim of this study was to assess the impact of transducer (loudspeaker, supra-aural headphones, and insert earphones) selection on the acceptable noise level (ANL). STUDY SAMPLE: Thirty young adults with normal hearing who reported difficulty with background noise served as participants. RESEARCH DESIGN: A repeated-measures experimental design was employed. DATA COLLECTION AND ANALYSIS: Most comfortable listening level (MCL) and background noise level (BNL) were measured for all participants using three transducers (loudspeaker, supra-aural headphones, and insert earphones). ANL was computed as the difference between the mean MCL and the mean BNL. RESULTS: Analytical statistics revealed that ANL did not differ due to the transducer used. However, there were statistically significant differences found for MCL and BNL across transducers. CONCLUSIONS: Results of this study indicate that ANL is not vulnerable to the selection of transducer and that ANLs can be compared across transducer types. Researchers should cautiously interpret findings across studies when discussing the base measures of MCL and BNL as these may be influenced slightly by transducer selection.

The Effect of Music Genre and Music-Preference Dimension on Acceptable Noise Levels in Listeners with 'Normal' Hearing.

BACKGROUND: The acceptable noise level (ANL) is the maximum level of background noise that an individual is willing to accept while listening to speech. The type of background noise does not affect ANL results except for music. PURPOSE: The purpose of this study was to determine if ANL differed due to music genre or music genre preference. RESEARCH DESIGN: A repeated-measures experimental design was employed. STUDY SAMPLE: Thirty-three young adults with normal hearing served as listeners. DATA COLLECTION AND ANALYSIS: Most comfortable listening level and background noise level were measured to twelve-talker babble and five music samples from different genres: blues, classical, country, jazz, and rock. Additionally, music preference was evaluated via rank ordering of genre and by completion of the Short Test of Music Preference (STOMP) questionnaire. RESULTS: The ANL for music differed based on music genre; however, the difference was unrelated to music genre preference. Also, those with low ANLs tended to prefer the intense and rebellious music-preference dimension compared with those with high ANLs. CONCLUSIONS: For instrumental music, ANL was lower for blues and rock music compared with classical, country, and jazz. The differences identified were not related to music genre preference; however, this finding may be related to the music-preference dimension of intense and rebellious music. Future work should evaluate the psychological variables that make up music-preference dimension to determine if these relate to our ANL.

Frequency Responses of Conventional and Amplified Stethoscopes for Measuring Heart Sounds.

BACKGROUND: Frequencies of normal and abnormal heart sounds have previously been reported, but the acoustic analyses of the frequency responses of conventional and amplified stethoscopes for different heart sounds have not yet been reported. OBJECTIVES: To compare the acoustic analysis of frequency responses of three stethoscopes (conventional and amplified) for measuring simulated heart sounds. MATERIALS AND METHODS: This exploratory study used Starkey SLI-ST3, Cardionics E-Scope II (both electronic) and Littmann Classic S.E. II (conventional) stethoscopes, as they share the same basic design with twin ear tubes coupled to ear tips and chest piece options (bell vs. diaphragm modes). Acoustic analyses using the diaphragm were performed in a soundproof booth and frequency response curves at 85 (the largest), 250, 400, 550 and 1050 Hz were compared for three different digitized heart sound simulations: normal, aortic valvular stenosis (AVS) and pulmonic valvular stenosis. RESULTS: Amplified stethoscopes provided the most amplification of normal and abnormal heart sounds across all five frequencies compared with the conventional stethoscope. The Starkey SLI-ST3 stethoscope was better at amplifying normal heartbeats than the Cardionics E-Scope II and Littman Classic S.E. II; however, it came last for amplifying normal heartbeats of ~85 Hz. Cardionics E-Scope II had advantages in amplifying abnormal heartbeats (i.e., aortic valvular stenosis and pulmonic valvular stenosis) over the other two stethoscopes. CONCLUSION: This study showed that amplified stethoscopes provided better amplification of normal and abnormal heart sounds across the five measured frequencies. Therefore, health professionals should interpret manufacturer claims regarding gain (dB) and frequency (Hz) with caution, and those with hearing loss should carefully investigate the "audio performance" of the stethoscopes. Future research should focus on these effects through coupling with hearing aids.

Acceptable Noise Level Stability Over a One-Year Period of Time.

BACKGROUND: The acceptable noise level (ANL) is a measure of willingness to listen to speech in the presence of background noise and is thought to be related to success with amplification. To date, ANLs have only been assessed over short periods of time, including within a session and over a 3-week and 3-month time period. ANL stability over longer periods of time has not been assessed. PURPOSE: The purpose was to examine the stability of ANL over a 1-year time period. RESEARCH DESIGN: A repeated-measures, longitudinal study was completed. STUDY SAMPLE: Thirty young adults with normal hearing served as participants. The participants were tested at two different sites. DATA COLLECTION AND ANALYSIS: Two trials of most comfortable listening levels (MCLs), background noise levels (BNLs), and ANLs were assessed for each participant during three experimental sessions: at 0 months, 6 months, and 1 year. RESULTS: Two-way repeated-measures analysis of variances revealed no significant change in MCLs, BNLs, or ANLs within a session or over a 1-year time period. These results indicate that ANLs remain stable for 1 year in listeners with normal hearing. CONCLUSIONS: The finding that the ANL is stable over a longer period of time supports the theory that the ANL is an inherent trait of the listener and mediated at in the central auditory nervous system.