A light-weight wireless omni-directional sound source for roomacoustic measurements
One of the biggest challenges in room acoustic measurements, according to the ISO 3382 standard (parts 1-3), is to use sources that maintain omnidirectional directivity (with small deviations) across the frequency range, from the 125 Hz to 4 kHz octave bands. Conventional omnidirectional sources can achieve adequately omnidirectional directivity with the use of more than […]
Meaningful acoustical parameters for open-air theatres
The reverberation time and other acoustical parameters defined in ISO 3382-1 have been derived with closed spaces in mind, and it is not obvious that the same parameters are meaningful in an open-air theatre. Low reflection density and lack of late reflections mean that the reverberation parameters are unreliable. It is necessary to re-think the […]
A revised theory for the absorption of a rectangular absorber in an infinite rigid baffle
The reverberation chamber method to measure a material’s absorption coefficient has known limitations. In particular, the measured value can exceed unity, due to the finite size of the studied sample, which creates edge diffraction effects. These are not accounted for in classical theories of absorption. A revised theoretical approach is proposed to evaluate the absorption […]
Estimation of the sound power of multiple sources using SPL measurements and room acoustic simulations
The sound power of sources is a key input to room acoustic simulations. However, existing measurement methods are generally unpractical as they require specific equipment, for instance a reverberation room in ISO 3743. A method is proposed to find the sound power spectrum of sources for room acoustic simulations, based on in situ sound pressure […]
Sound strength measurements using a pre-calibrated omnidirectional source
Most room acoustic parameters are derived from the shape and slope of the measured energy decay curve, regardless of the actual sound level. However, several parameters, such as Sound Strength 𝐺𝐺 and Speech Transmission Index STI, are based on the actual sound pressure level at the receiver position and can only be derived using a […]
Room acoustic measurement methods in the past, present and future, including the importance of the ISO 3382 series
The measurement of reverberation time in a room was introduced by W.C. Sabine a few years before 1900 with the purpose to handle acoustic problems in a lecture theatre. The sound source was organ pipes at the seven octave frequencies from 63 Hz to 4000 Hz. Later, the measurements were greatly improved by using interrupted […]
Room acoustic measurements in a swimming hall at different atmospheric conditions
When measuring the reverberation time in a room, it is well known that the result, especially at high frequencies, depends on the temperature and relative humidity (RH) of the air. Room acoustic measurements were made with the integrated impulse response method in a swimming hall under different atmospheric conditions, ranging from 31,2 °C and 88,1 […]
Sound reflections
The present paper is a review of the author’s work on sound reflections covering a span of years starting from 1982. After a study of the reflection properties of curved surfaces, the diffraction effects related to single reflectors was studied, both theoretically and experimentally. The main result was a characteristic frequency above which the sound […]
