Maximal Ambient Noise Levels and Type of Voice Material Required for Valid Use of Smartphones in Clinical Voice Research.
OBJECTIVE
Smartphone technology provides new opportunities for recording standardized voice samples of patients and transmitting the audio files to the voice laboratory. This drastically improves the achievement of baseline designs, used in research on efficiency of voice treatments. However, the basic requirement is the suitability of smartphones for recording and digitizing pathologic voices (mainly characterized by period perturbations and noise) without significant distortion. In a previous article, this was tested using realistic synthesized deviant voice samples (/a:/) with three precisely known levels of jitter and of noise in all combinations. High correlations were found between jitter and noise to harmonics ratio measured in (1) recordings via smartphones, (2) direct microphone recordings, and (3) sound files generated by the synthesizer. In the present work, similar experiments were performed (1) in the presence of increasing levels of ambient noise and (2) using synthetic deviant voice samples (/a:/) as well as synthetic voice material simulating a deviant short voiced utterance (/aiuaiuaiu/).


RESULTS
Ambient noise levels up to 50 dBAare acceptable. However, signal processing occurs in some smartphones, and this significantly affects estimates of jitter and noise to harmonics ratio when formant changes are introduced in analogy with running speech. The conclusion is that voice material must provisionally be limited to a sustained /a/.
Neurosciences Institute, University of Louvain, Brussels, Belgium.
Jean
J
Lebacq
B.E.A.M.S. Department, Faculty of Applied Sciences, Université Libre de Bruxelles, Brussels, Belgium.
Jean
J
Schoentgen
Otolaryngology Department, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milano, Italy.
Giovanna
G
Cantarella
Department of Mathematics, Université Libre de Bruxelles, Brussels, Belgium.
Franz Thomas
FT
Bruss
Department of Information Engineering, Università degli Studi di Firenze, Firenze, Italy.
Claudia
C
Manfredi
Neurosciences, University of Leuven (KULeuven) and FEDRIS (Federal Agency for Occupational Risks), Brussels, Belgium. Electronic address: philippe.dejonckere@kuleuven.be.
Philippe
P
DeJonckere
D000162:Acoustics / Q000295:instrumentation*; D006801:Humans; D009622:Noise / Q000009:adverse effects; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D059629:Signal-To-Noise Ratio; D000068997:Smartphone; D013018:Sound Spectrography; D013061:Speech Acoustics; D013068:Speech Production Measurement / Q000295:instrumentation* / Q000379:methods; D013066:Speech-Language Pathology / Q000295:instrumentation* / Q000379:methods; D013997:Time Factors; D014832:Voice Disorders / Q000175:diagnosis* / Q000503:physiopathology; D014833:Voice Quality
Acoustics; Dysphonia; Noise; Recording; Smartphone