ASA 125th Meeting Ottawa 1993 May

3pAA5. Noise isolation measurements of partitions and windows under highly absorptive and flanking conditions in the field.

Angelo J. Campanella

Campanella Assoc., 3201 Ridgewood Dr., Columbus, OH 43026

Installed partitions, windows, and doors are often not situated ideally for sound isolation performance testing in terms of ASTM E 90 laboratory sound transmission loss (TL) and STC values. Test room quality specified in the ASTM E 336 and E 966 field methods may preclude TL measurement due to high absorption, small size, or flanking. Methods of Buckingham [NBS SP 20, 193--219 (S-506)], London [NBS RP 26, 419--453 (RP 1338) (1941)], and Donato [J. Acoust. Soc. Am. 40, 1--3 (1966)] were examined for field tests. Buckingham proposed the room space average sound-level method now used in ASTM E 90, ASTM E 336, and E 966. Donato proposed that a term of value 1/8 be added within the 10 log (S/A) absorption normalization term to account for direct sound. London proposed sound-pressure level measurements (SPL) flush to the specimen receiving room surface for field tests. Flush SPL can be normalized with receiver room space average SPL or absorption via RT60 to determine TL. Tests were recently performed on four windows installed in field conditions ranging from high absorption with no flanking to very large reverberant spaces with flanking. The flush SPL method combined with RT60 normalization provided the most credible results for comparison with laboratory STC, and also offered immunity to flanking. Data and comparative results will be presented.