IMPORTANCE OF ACOUSTICS AND MEASUREMENTS
Acoustical Measurements help us analyze acoustical parameters of a room that can help the user take informed decisions about the acoustical conditions of that room.
Different rooms and areas have different pre-requisites in terms of audio. For example, office spaces, auditoriums, recording studios, clubs etc have different sound pressure level requirements and also acoustical isolation requirements. Furthermore, for most of these spaces, these acoustical parameters are described in publication of International Standards (Eg. IEC / ISO ).
1) Reverberation Time:
The reverberation time of a room or space is defined as the taken by the sound in a room to decay by 60dB. For example, if the sound in a room takes 10 seconds to decay from 100dB to 40dB, the reverberation time would be 10 seconds. This can also be written as the T60 time.
Example:
The following are the measured values of EDT, RT20 and RT30 at a site.
RT60 = ( time to decay 30 dB ) * 2
We can see that there is a rise in the frequency bands 80Hz-250Hz which gradually tapers down. T30 at 125Hz band is around 1.2 seconds.
These values can be imported into other acoustical simulation softwares for further analysis to make accurate predictions.
2) Speech Transmission Intelligibility (STI)
STI is defined as a measure of Speech Transmission Quality. It is rated on a 0-1 scale as shown below.
The STI calculated is affected by many parameters such as :
• SPL
• Acoustical parameters of the room in consideration
• Frequency response of the channel
• Background / ambient noise level
• Quality of equipment used
• Masking effects
• Reverberation time etc.
Some of our projects with Acoustic/Sound Proofing Solutions
ACOUSTICAL MEASUREMENTS:
We are equipped with Class 1 Sound Level Measurements compliant with ANSI S1.4 and IEC61762-1:2014.
Acoustical measurements taken for further analysis are:
1) Sound Pressure Level (SPL) at different points in the auditorium seating areas.
2) Reverberation Time (RT60) – T20, T30.
3) Noise Criterion (NC) value of the room.
4) Real-Time Analysis (RTA) with 1/1, 1/3, 1/6 and 1/12 octave resolution. Compliant to IEC-61260- 1:2014
5) Speech Transmission Index (STI) , STIPA, STI full method compliant to IEC-60268-16 edition 4/5 standards.
6) Sound Transmission Class (STC) for identification of audio leakage between rooms and acoustical isolation between rooms.
7) Loudspeaker Polarity identification.
Upon measurements, a report is generated and submitted to the client. The scope of measurement work ends here.
ACOUSTICAL SIMULATION AND ANALYSIS with AFMG EASE Software:
1) Designing of the room with acoustical treatment
2) Reverberation time after treatment based on chosen acoustical treatment materials.
3) Speech Transmission Index (STI) of the hall as per IEC 60268-16 Ed4 standards.
4) Articulation Loss of Consonants (Alcons %) to identify clarity losses in speech.
5) Sound Pressure Level dispersion across the entire seating area to ensure all areas of seating gets even audio coverage.
6) SPL dispersion across multiple frequencies.
7) Incorporation of audio equipment (loudspeakers) in the hall to ensure perfect coverage, tonality, time alignment etc.
Scope of this work ends with submission of the EASE report that includes all information on the necessary acoustical treatment. 3 site visits will be needed.
AUDIO SYSTEM TUNING:
We are also equipped with industry standard audio tuning and measurement softwares and hardware to tune the proposed audio system via the DSP provided.
Tuning is done via RTA measurements, Transfer Function Analysis, Polarity Check, Time Delay adjustments between speaker components, Waterfall graph analysis and gain shading.
This ensures that the installed audio system sounds perfect for multipurpose applications. Upon acoustical measurement and analysis, we shall be able to perfectly identify all tonal issues in the room and take necessary steps to ensure perfect audio coverage across the space.