We are hap­py to announce that our paper “Asym­me­tries in the pro­cess­ing of vow­el height” will be appear­ing in the Jour­nal of Speech, Lan­guage, & Hear­ing Research, authored by Philip Mon­a­han, William Idsar­di and Math­ias Scharinger. A short sum­ma­ry is giv­en below:

Pur­pose: Speech per­cep­tion can be described as the trans­for­ma­tion of con­tin­u­ous acoustic infor­ma­tion into dis­crete mem­o­ry rep­re­sen­ta­tions. There­fore, research on neur­al rep­re­sen­ta­tions of speech sounds is par­tic­u­lar­ly impor­tant for a bet­ter under­stand­ing of this trans­for­ma­tion. Speech per­cep­tion mod­els make spe­cif­ic assump­tions regard­ing the rep­re­sen­ta­tion of mid vow­els (e.g., []) that are artic­u­lat­ed with a neu­tral posi­tion in regard to height. One hypoth­e­sis is that their rep­re­sen­ta­tion is less spe­cif­ic than the rep­re­sen­ta­tion of vow­els with a more spe­cif­ic posi­tion (e.g., [æ]).

Method: In a mag­ne­toen­cephalog­ra­phy study, we test­ed the under­spec­i­fi­ca­tion of mid vow­el in Amer­i­can Eng­lish. Using a mis­match neg­a­tiv­i­ty (MMN) par­a­digm, mid and low lax vow­els ([]/[æ]), and high and low lax vow­els ([I]/[æ]), were opposed, and M100/N1 dipole source para­me­ters as well as MMN laten­cy and ampli­tude were examined.

Results: Larg­er MMNs occurred when the mid vow­el [] was a deviant to the stan­dard [æ], a result con­sis­tent with less spe­cif­ic rep­re­sen­ta­tions for mid vow­els. MMNs of equal mag­ni­tude were elicit­ed in the high–low com­par­i­son, con­sis­tent with more spe­cif­ic rep­re­sen­ta­tions for both high and low vow­els. M100 dipole loca­tions sup­port ear­ly vow­el cat­e­go­riza­tion on the basis of lin­guis­ti­cal­ly rel­e­vant acoustic–phonetic features.

Con­clu­sion: We take our results to reflect an abstract long-term rep­re­sen­ta­tion of vow­els that do not include redun­dant spec­i­fi­ca­tions at very ear­ly stages of pro­cess­ing the speech sig­nal. More­over, the dipole loca­tions indi­cate extrac­tion of dis­tinc­tive fea­tures and their map­ping onto rep­re­sen­ta­tion­al­ly faith­ful cor­ti­cal loca­tions (i.e., a fea­ture map).

The paper is avail­able here.