This is the sound absorption coefficient of the soundproofing material when sound energy enters to the sound insulation material from various direction. It is an index commonly used for automotive sound absorptive materials and building materials.

- Complying industrial standards: JIS A 1409 and ISO 354
- Size of specimen: 1.0 m x 1.0 m (ask for other sizes)
- Frequency range: 400Hz to 5,000Hz

Set the specimen in the opening of the reverberation chamber and the anechoic chamber and measure the sound transmission loss (sound insulation performance) of the material. It is an index commonly used for automotive sound absorptive materials and building materials.

- Complying industrial standards: JIS A 1441-1 and ISO 15186-1
- Size of specimen: 0.6 m x 0.6 m or 1.0 m x 1.0 m
- Frequency range: 400Hz to 5,000Hz

Measure the sound absorption coefficient under the condition that sound is incident perpendicular to the material. It is characterized by being able to evaluate with a small sample using a device called “impedance tube”. It is a method that is used in evaluation at the material development stage.

- Complying industrial standards: JIS A 1405-2, ISO 10534-2, and ASTM E1050、
- Size of specimen: cut cylindrically with 40 mm or 15 mm in diameter
- Frequency range: 100Hz to 5,000Hz (40mm diameter), 4,000Hz ~ 12,500Hz (15 mm in diameter)

Measure the sound transmission loss under the condition that sound is incident perpendicular to the material. It is characterized by being able to evaluate with a small sample using a device called “impedance tube”, but this method is applicable for porous materials only.

- Complying industrial standards: ASTM E2611
- Size of specimen: cut cylindrically with 40 mm in diameter
- Frequency range: 100Hz to 5,000Hz