Voice parameter changes in professional musician-singers singing with and without an instrument: the effect of body posture

BACKGROUND AND AIM: The impact of body posture on vocal emission is well known. Postural changes may increase muscular resistance in tracts of the phono-articulatory apparatus and lead to voice disorders. This work aimed to assess whether and to which extent body posture during singing and playing a musical instrument impacts voice performance in professional musicians. SUBJECTS AND METHODS: Voice signals were recorded from 17 professional musicians (pianists and guitarists) while they were singing and while they were singing and playing a musical instrument simultaneously. Metrics were extracted from their voice spectrogram using the Multi-Dimensional Voice Program (MDVP) and included jitter, shift in fundamental voice frequency (sF0), shimmer, change in peak amplitude, noise to harmonic ratio, Voice Turbulence Index, Soft Phonation Index (SPI), Frequency Tremor Intensity Index, Amplitude Tremor Intensity Index, and maximum phonatory time (MPT). Statistical analysis was performed using two-tailed t tests, one-way ANOVA, and χ2 tests. Subjects' body posture was visually assessed following the recommendations of the Italian Society of Audiology and Phoniatrics. Thirty-seven voice signals were collected, 17 during singing and 20 during singing and playing a musical instrument. RESULTS: Data showed that playing an instrument while singing led to an impairment of the "singer formant" and to a decrease in jitter, sF0, shimmer, SPI, and MPT. However, statistical analysis showed that none of the MDVP metrics changed significantly when subjects played an instrument compared to when they did not. Shoulder and back position affected voice features as measured by the MDVP metrics, while head and neck position did not. In particular, playing the guitar decreased the amplitude of the "singer formant" and increased noise, causing a typical "raucous rock voice." CONCLUSIONS: Voice features may be affected by the use of the instrument the musicians play while they sing. Body posture selected by the musician while playing the instrument may affect expiration and phonation.