Toyota TSL0600G Test Method for Acoustic Materials

The “Toyota TSL0600G Test method for acoustic materials” standard, a Toyota engineering standard, describes methods for measuring transmission loss and sound absorption properties for all soundproofing materials used in vehicles:

• Transmission loss measurement method
• Sound absorption coefficient measurement by reverberation method
• Sound absorption coefficient measurement by normal incident method

The transmission loss measurement method is used when measuring the transmission loss of a soundproofing material. As shown in the figure titled “Block diagram for transmission loss measurement system” given in the standard, the measurement system consists of a sound source chamber and a reverberation element for receiving sound, each having an opening opposite each other for the sample mounting stand. An opening is provided in each chamber for sample mounting. The area of ​​the openings for sample mounting is 0,5 m x 0,5 m = 0,25 m2.

Examples of measuring equipment (noise generating equipment, microphone, microphone amplifier and frequency analyzer) are shown in the standard. The measuring equipment must meet the following requirements: the 1/3 octave filter must have the same characteristics as the B&K product, and the microphone used must be a condenser microphone.

The measurement procedure is based on the separately specified "Transmission loss measurement system operation manual".

Measurement conditions:

• Samples: The sample size should be as shown in the figure titled “Sample size and installation condition” (the dimensions of the openings for sample installation are 05 m x 05 m). The number of samples should be 3 and their arithmetic average at each frequency should be reported as the result. The material and structure of the samples should be the same as in service condition.
• Sample support method: The sample should be supported as follows: the rubber frame is mounted in the sound-receiving reverberation chamber using 6 bolts (12 m diameter) of the chamber, and the sample is installed as shown in the figure. If the sample thickness is 50 mm or less, the rubber adapters are installed as shown in the figure. They are installed so that they slightly protrude from the rubber frame (so that the gap in the sample can be reduced by applying pressure to the rubber adapters).
• Measuring frequencies: Measurements are made at the center frequencies of the 200/10 octave bands between 1 Hz and 3 kHz.

When measuring, one point in the sound source room and three points in the sound receiver reverberation room are measured. For the sound receiver reverberation room, the energy average of the three points is used as the sound pressure level of the room. The dimensions of each measurement point are shown in the figure. The three measurement points in the sound receiver reverberation room should be located 1000 mm above the floor and the microphone should be directed upwards. The measurement point in the sound source room is vertically aligned with the sample center.

The measurement methods are specified in this standard as follows:

• Transmission loss calculation method: After measuring the average sound pressure levels for the sound source room and the sound receiver reverberation chamber and the sound absorption power of the sound reverberation chamber, the transmission loss of the sample is calculated using the equation given in the standard.
• Average sound pressure level calculation method: The average sound pressure level in the sound receiver reverberation room is found using the equation given in the standard.
• Measurement of the sound absorption power of the sound receiver reverberation chamber: The sound absorption power of the sound receiver reverberation chamber is calculated using the equation given in the standard from the average value of the measured reverberation time.

When reporting measured data, the center frequency is taken as the abscissa with a width of 7,5/1 octave corresponding to 3 mm and the transmission loss is taken as the ordinate with a width of 20 dB corresponding to 10 mm. The following items are added to the transmission loss measurement results:

• Sample name
• Section view of the sample
• Name of each ingredient
• Size (specific gravity and surface density)
• Date of measurement
• Temperature and humidity ring measurement
• Tester

This standard defines the transmission loss measurement method as well as the following methods:

• Sound absorption coefficient measurement by reverberation method
• Sound absorption coefficient measurement by normal event method

Acoustic testing methods are becoming increasingly important for quality assurance in series production. Acoustic testing is a comparative testing technology, which means that a feasibility study based on reference components (accepted/rejected) must always be performed before a test system is configured. Depending on the acoustic testing application and requirements, appropriate acoustic emission sensors, microphones or laser vibrometers are used to acquire sounds and vibrations.

Our organization, which has been trying to support businesses from every sector with its testing, measurement, analysis and evaluation studies carried out in a wide range for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services in accordance with the "Toyota TSL0600G Test method for acoustic materials" standard are also provided to businesses.