An international comparison of long-term average speech spectra

TLDR

The study measured long‑term average speech spectra (LTASS) and dynamic characteristics for 12 languages plus Arabic LTASS, using 18 standardized recordings from 15 locations with roughly ten male and ten female speakers each, and performed all analyses at the National Acoustic Laboratories in Sydney. LTASS values were broadly similar across languages, yet numerous statistically significant but small and gender‑inconsistent differences were observed, and one‑third octave bands consistently showed a 10‑dB higher short‑term rms level than long‑term, supporting the proposal of a universal LTASS for hearing‑aid prescription and the Articulation Index.

Abstract

The long-term average speech spectrum (LTASS) and some dynamic characteristics of speech were determined for 12 languages: English (several dialects), Swedish, Danish, German, French (Canadian), Japanese, Cantonese, Mandarin, Russian, Welsh, Singhalese, and Vietnamese. The LTASS only was also measured for Arabic. Speech samples (18) were recorded, using standardized equipment and procedures, in 15 localities for (usually) ten male and ten female talkers. All analyses were conducted at the National Acoustic Laboratories, Sydney. The LTASS was similar for all languages although there were many statistically significant differences. Such differences were small and not always consistent for male and female samples of the same language. For one-third octave bands of speech, the maximum short-term rms level was 10 dB above the maximum long-term rms level, consistent across languages and frequency. A ‘‘universal’’ LTASS is suggested as being applicable, across languages, for many purposes including use in hearing aid prescription procedures and in the Articulation Index.