I found this at
http://www.livingunderworld.org/biology/caudata.htm
Auditory and Vocal Function
Salamanders lack eardrums and the middle ear cavity, but possess functional sensory reception areas in the inner ear. In adults, the columella is fused to the skull, but is motile in larvae. Primitive Cryptobranchid and Hynobiid salamanders possess basilar papilla and amphibian papilla, whereas the basilar papilla is absent or reduced in the advanced salamanders. The absence or reduction of the basil papilla appears to be related to the lack of a tympanic-middle ear sound transmission system, and the lack of communication by vocal sound. Low frequency sounds can be detected by salamanders due to a suitable suprascapular-opercular link.
Larvae and aquatic individuals possess mechanoreceptive neuromasts, or the lateral line system. The later line system is also present in most fish, and consists of hair cells appearing as pit-like depressions in the skin, running from the head to the tail. In dark colored salamanders and newts, and some larvae, the lateral line system can be seen as light colored, perforated lines running dorsolaterally along the individual. The hair cells register water current and pressure changes, allowing the animal to detect even slight water movements at, or under, the surface. In most aquatic caudates, ampullary organs are also present in the lateral line system, which function as electroreceptors.
All salamanders, with the exception of one species, are incapable of producing sounds due to the lack of vocal sacs, folds, and chords. Dicamptodon ensatus, the one exception, possesses vocal folds and has been noted as making squeeking sounds when disturbed. However, it is thought that the sounds actually result from air being forced through gill slits or nares, which creates a vacuum during inspiration.}}
