# Acoustic Changes in Voicemail Transmission Induced by Mobile Phones

## TL;DR

This study shows that mobile phones significantly alter voice recordings in voicemail transmissions, with some acoustic features being more affected than others.

## Contribution

The study provides empirical evidence of specific acoustic changes caused by mobile phones during voicemail transmission.

## Key findings

- Fundamental frequency (Fo) was not significantly altered by mobile phone transmission.
- Amplitude perturbation and noise parameters were significantly affected by mobile phone transmission.
- Frequency perturbation parameters showed moderate changes during voicemail transmission.

## Abstract

Given the widespread use of mobile phones for voice communication, a comprehensive understanding of the objective acoustic alterations in voicemail transmission is lacking, motivating this investigation into voice quality changes.

This study aims to explore the objective changes in voice recordings caused by mobile phones and voicemail applications during the transmission process, specifically focusing on the alterations to voice quality that occur during this process.

A volunteer sample of 45 healthy male hospital employees, with an average age of 36.7 ± 7.5 (ranging from 22 to 50), in a tertiary referral center were included in this study. The Multi-Dimensional Voice Program (Kay Elemetrics, Lincoln Park, NJ, USA) was employed to compare a set of nine parameters derived from sustained vowel phonations of /a/, encompassing free-field voice and mobile phone voicemail recordings. Average fundamental frequency (Fo), frequency perturbation parameters [Pitch Period Perturbation Quotient (PPQ), Relative Average Perturbation (RAP)], amplitude perturbation parameters [Shimmer in dB (ShdB), Shimmer Percent (Shim), Amplitude Perturbation Quotient (APQ)], noise parameters [Noise-to-Harmonic Ratio (NHR)] were calculated.

Analysis of the patient data revealed that fundamental frequency (Fo) was resistant to alterations of voice (
p
 = 0,313). Frequency perturbation parameters (PPQ, RAP) were impacted (
p
 = 0.018, 0.020 respectively), however, amplitude perturbation parameters (ShdB, Shim, APQ) and noise parameter (NHR) were much more affected in voice transmission caused by mobile phones (
p
 < 0,001 in all).

The findings of this study indicate that mobile phones induce significant acoustic changes in voicemail transmission. The fundamental frequency remained resistant to alterations in voice.