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

Abstract

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.

Keywords

sound levels - calibration - smartphone - sound level meter - sound level meter applications

• References

• 1 Beattie RC. Word recognition functions for the CID W-22 test in multitalker noise for normally hearing and hearing-impaired subjects. J Speech Hear Disord 1989; 54 (01) 20-32
• 2 Dubno JR, Dirks DD, Morgan DE. Effects of age and mild hearing loss on speech recognition in noise. J Acoust Soc Am 1984; 76 (01) 87-96
• 3 McArdle RA, Wilson RH, Burks CA. Speech recognition in multitalker babble using digits, words, and sentences. J Am Acad Audiol 2005; 16 (09) 726-739 , quiz 763–764
• 4 Wilson RH. Development of a speech-in-multitalker-babble paradigm to assess word-recognition performance. J Am Acad Audiol 2003; 14 (09) 453-470
• 5 American National Standards Institute. Maximum Permissible Ambient Noise Levels for Audiometric Test Rooms (Rev. ed.; ANSI S3.1–1999). New York, NY: Author; 2018
• 6 American Academy of Audiology. Childhood Hearing Screening Guidelines. 2011 . Accessed October 27, 2020 at: https://audiologyweb.s3.amazonaws.com/migrated/ChildhoodScreeningGuidelines.pdf_5399751c9ec216.42663963.pdf
• 7 American Speech-Language-Hearing Association. Childhood Hearing Screening. n.d. Accessed September 2, 2020 at: https://www.asha.org/practice-portal/professional-issues/childhood-hearing-screening/
• 8 American National Standards Institute. Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools, Part 1: Permanent Schools (S12.60.2010/Part 1). New York, NY: Author; 2010
• 9 Celestina M, Hrovat J, Kardous CA. Smartphone-based sound level measurement apps: evaluation of compliance with international sound level meter standards. Appl Acoust 2018; 139: 119-128
• 10 Kardous CA, Shaw PB. Evaluation of smartphone sound measurement applications. J Acoust Soc Am 2014; 135 (04) EL186-EL192
• 11 Kardous CA, Shaw PB. Evaluation of smartphone sound measurement applications (apps) using external microphones-a follow-up study. J Acoust Soc Am 2016; 140 (04) EL327-EL333
• 12 Keene K, Merovitz A, Irvine E. et al. Accuracy of smartphone sound level meter applications. Canad Hear Rep 2013; 8: 24-28
• 13 Murphy E, King EA. Testing the accuracy of smartphones and sound level meter applications for measuring environmental noise. Appl Acoust 2016; 106: 16-22
• 14 Nast DR, Speer WS, Le Prell CG. Sound level measurements using smartphone “apps”: useful or inaccurate?. Noise Health 2014; 16 (72) 251-256
• 15 Roberts B, Kardous C, Neitzel R. Improving the accuracy of smart devices to measure noise exposure. J Occup Environ Hyg 2016; 13 (11) 840-846
• 16 Robinson D, Tingay J. Comparative study of the performance of smartphone-based sound level meter apps, with and without the application of a 1 2 ″IEC-61094–4 working standard microphone, to IEC-61672 standard metering equipment in the detection of various problematic workplace noise environments. In Proceedings of the Inter Noise Conference. 2014, November. Accessed September 2, 2020 at: https://www.acoustics.asn.au/conference_proceedings/INTERNOISE2014/papers/p565.pdf
• 17 National Institute for Occupational Safety and Health. NIOSH Sound Level Meter App. 2019. Accessed September 2, 2020 at: https://www.cdc.gov/niosh/topics/noise/app.html
• 18 International Electrotechnical Commission. Electroacoustics Sound Level Meters, Part 3: Periodic Tests, Standard (IEC 61672–3). Geneva, Switzerland: Author; 2013
• 19 Fava G, Oliveira G, Baglione M, Pimpinella M, Spitzer JB. The use of sound level meter apps in the clinical setting. Am J Speech Lang Pathol 2016; 25 (01) 14-28
• 20 Serpanos YC, Renne B, Schoepflin JR, Davis D. The accuracy of smartphone sound level meter applications with and without calibration. Am J Speech Lang Pathol 2018; 27 (04) 1319-1328
• 21 American National Standards Institute. Measurement of Sound Pressure Levels in Air (Rev. ed.; ANSI S1.13–2005). New York: Author; 2010
• 22 American National Standards Institute. Sound Level Meters - Part 1: Specifications (A Nationally Adopted International Standard) (ANSI S1.4/Part1). New York, NY: Author; 2014