 The ability of the tympanum and stapes to effectively transmit vibrations is called impedance matching . Early tetrapods like temnospondyls have thick stapes with poor impedance matching , so it is now thought that they were not used for hearing . Instead , these thick stapes may have functioned to support the tissue that covers the otic notch . Early temnospondyls like Dendrerpeton could not hear airborne sound but would have been able to detect vibration in the ground . Later temnospondyls like Doleserpeton had otic regions adapted to hearing . Doleserpeton has a structure in the inner ear called the perilymphatic duct , which is also seen in frogs and is associated with hearing . Its stapes is also a better transmitter of sound . The hearing system of Doleserpeton and related temnospondyls was able to detect airborne sound and may have been ancestral to that of living amphibians . 
 The ability of the tympanum and stapes to effectively transmit vibrations is called impedance matching . Early tetrapods like temnospondyls <a href='got' title='1'><mark>have</mark></a> thick stapes with poor impedance matching , so it is now thought that they <a href='uninflect' title='2'><mark>were</mark></a> not used for <a href='negative_concord' title='3'><mark>hearing</mark></a> . Instead , these thick stapes may <a href='been_done' title='4'><mark>have</mark></a> functioned to support the tissue <a href='null_relcl' title='5'><mark>that</mark></a><a href='uninflect' title='6'><mark>covers</mark></a> the otic notch . Early temnospondyls like Dendrerpeton could not hear airborne sound but would have been able to detect vibration in the ground . Later temnospondyls like Doleserpeton had otic regions adapted to hearing . Doleserpeton <a href='got' title='7'><mark>has</mark></a> a structure in the inner ear called the perilymphatic duct , which is also seen in frogs and is associated with hearing . Its stapes <a href='drop_aux' title='8'><mark>is</mark></a>also a better transmitter of sound . The hearing system of Doleserpeton and related temnospondyls was able to detect airborne sound and may have been ancestral to that of living amphibians . 
The ability of the tympanum and stapes to effectively transmit vibrations is called impedance matchin . Early tetrapods like temnospondyls got thick stapes with poor impedance matching , so it is now thought that they was not used for no hearing . Instead , these thick stapes may done functioned to support the tissue cover da otic notch . Early temnospondyls like Dendrerpeton could not hear airborne sound but would have been able to detect vibration in the ground . Later temnospondyls like Doleserpeton had otic regions adapted to hearin . Doleserpeton got a structure in the inner ear called the perilymphatic duct , which is also seen in frogs and is associated wit hearing . Its stapes also a better transmitter of sound . The hearing system of Doleserpeton and related temnospondyls was able to detect airborne sound and may have been ancestral to that of living amphibians .