The Accuracy of Smartphone Sound Level Meter Applications (SLMAs) in Measuring Sound Levels in Clinical Rooms.

BACKGROUND: The accuracy of smartphone sound level meter applications (SLMAs) has been investigated with varied results, based on differences in platform, device, app, available features, test stimuli, and methodology. PURPOSE: This article determines the accuracy of smartphone SLMAs with and without calibration of external and internal microphones for measuring sound levels in clinical rooms. RESEARCH DESIGN: Quasi-experimental research design comparing the accuracy of two smartphone SLMAs with and without calibration of external and internal microphones. DATA COLLECTION AND ANALYSIS: Two iOS-based smartphone SLMAs (NIOSH SLM and SPL Meter) on an iPhone 6S were used with and without calibrated external and internal microphones. Measures included: (1) white noise (WN) stimuli from 20 to 100 dB sound pressure level in a sound-treated test booth and (2) sound levels in quiet in four nonsound-treated clinical rooms and in simulated background sound conditions using music at 45, 55, and 80 dBA. Chi-square analysis was used to determine a significant difference (p ≤ 0.05) in sound measures between the SLMAs and a Type 1 SLM. RESULTS: Measures of WN signals and room sound level measures in quiet and simulated background sound conditions were significantly more accurate at levels ≥ 40 dBA using the SLMAs with calibrated external and internal microphones. However, SLMA measures with and without calibration of external and internal microphones overestimated sound levels < 40 dBA. CONCLUSION: The SLMAs studied with calibrated external or internal microphones are able to verify the room environment for audiologic screening at 1,000, 2,000, and 4,000 Hz at 20 dB hearing level (American Academy of Audiology and American Speech-Language-Hearing Association) using supra-aural earphones (American National Standards Institute S3.1-1999 [R2018]). However, the tested SLMAs overestimated low-level sound < 40 dBA, even when the external or internal microphones were calibrated. Clinicians are advised to calibrate the microphones prior to using measurement systems involving smartphones and SLMAs to measure room sound levels and to monitor background noise levels throughout the provision of clinical services.

The Accuracy of Smartphone Sound Level Meter Applications With and Without Calibration.

Purpose: The purpose of this study is to determine the accuracy of smartphone sound level meter applications (SLMAs) with calibration features across stimulus levels and for ambient room noise measures in the clinical setting. Method: The accuracy of 3 iOS-based smartphone SLMAs (SLMA1: Analyzer [Version 2.7.2, DSP Mobile], SLMA2: Sound Level Meter Pro [Version 2.2, Mint Muse LLC], and SLMA3: SPL Meter [Version 9.3, Andrew Smith, Studio Six Digital]), using a single smartphone device (iPhone 6S Model A1688, iOS 9.3.4, Apple), was evaluated with and without calibration using a 1000-Hz narrowband noise (NBN) and white noise (WN) stimuli over a range of sound levels (20-100 dB) and in ambient noise measures of 8 speech and hearing room environments. A simultaneous and corresponding SLMA and Type 1 sound level meter (SLM) measure per condition were documented with a photo image; each condition was replicated 5 times. Mean SLMA and SLM measures were compared. SLMA measures were considered accurate if within ± 2 dB of the SLM. Results: Measures of NBN and WN signals using these SLMAs were accurate at levels above 40-50 dB when calibrated. NBN and WN signals using some SLMAs were significantly (p < .05) more accurate with calibration at levels > 40 to 50 dB. SLMA measures with or without calibration adjustment were inaccurate and overestimated room ambient noise levels < 50 dB. Conclusions: These findings suggest that some SLMAs are accurate for measuring NBN and WN stimuli within the range of 50-100 dB in sound-treated environments when calibrated. However, outcomes indicated that some SLMAs, even with calibration, overestimated low ambient noise levels and may not accurately verify quiet room environments < 50 dB for clinical services. These results should not be generalized for all smartphone types, and continued research on SLMAs using next-generation smartphone devices is warranted.

Binaural interference in a child: a case study.

A case study of a child (KB) who demonstrated binaural interference is reported. KB wore unilateral amplification from 1.6 to 4.6 years of age, at which time word-recognition scores under phones were markedly asymmetric, reflecting significantly better performance for the aided ear than the unaided ear, despite similar unaided pure-tone sensitivity. Suspecting the asymmetry in word-recognition performance might be the result of auditory deprivation, bilateral amplification was prescribed at 4.6 years of age. Three months later, adverse changes in the child's behavior were reported. At 5.3 years, significant interaural asymmetry was noted in word-recognition scores under phones, in unilateral-aided word-recognition scores (90% vs. 36%), and in the bilateral-aided score (56%), supporting the presence of binaural interference.

Auditory deprivation in adults with asymmetric, sensorineural hearing impairment.

The purpose of this investigation was to prospectively examine performance on the pure-tone air-conduction threshold, speech-recognition threshold, and suprathreshold word-recognition tests over time in 21 monaurally aided (experimental group) and 28 unaided adults (control group) with asymmetric, sensorineural hearing impairment. The results revealed significant declines on the mean suprathreshold word-recognition scores over time at one and two years post-baseline for the worse ears of the control participants; no declines occurred in the worse ears of the experimental participants or in the better ears of either group. A slight, significant increase in the pure-tone average occurred for the better ears of both groups. The findings are consistent with the presence of an auditory deprivation effect on suprathreshold word-recognition ability in the control group, suggesting that lack of amplification leads to decline in word-recognition performance over time in the worse ears of adults with asymmetric sensorineural hearing impairment.