Fascinating new research by my University of Chicago colleague, Jeffrey Grogger, compares the wages of people who “sound black” when they talk to those who do not.

His main finding: blacks who “sound black” earn salaries that are 10 percent lower than blacks who do not “sound black,” even after controlling for measures of intelligence, experience in the work force, and other factors that influence how much people earn. (For what it is worth, whites who “sound black” earn 6 percent lower than other whites.)

How does Grogger know who “sounds black?” As part of a large longitudinal study called the National Longitudinal Survey of Youth, follow-up validation interviews were conducted over the phone and recorded.

Grogger was able to take these phone interviews, purge them of any identifying information, and then ask people to try to identify the voices as to whether the speaker was black or white. The listeners were pretty good at distinguishing race through voices: 98 percent of the time they got the gender of the speaker right, 84 percent of white speakers were correctly identified as white, and 77 percent of black speakers were correctly identified as black.

Grogger asked multiple listeners to rate each voice and assigned the voice either to a distinctly white or black category (if the listeners all tended to agree on the race), or an indistinct category if there was disagreement.

Then he put this measure of whether a voice sounded black into a regression (the standard statistical tool that economists use for estimating things), and came up with the finding that blacks who “sound black” earn almost 10 percent less, even after taking into account other factors that could influence earnings. One piece of interesting good news is that blacks who do not “sound black” earn essentially the same as whites.

(It turns out you don’t want to sound southern, either. Although pretty imprecisely estimated, it is almost as bad for your wages to sound southern as it is to sound black, even controlling for whether you live in the south.)

So what does this all mean?

The first question to ask is whether the impact of speech on wages is a causal one. It is possible that there are many other characteristics that differ between blacks who do or do not “sound black” that Grogger cannot control for in his regressions. It does seem likely that the biases at work would make his estimate an upper bound. (Although it should also be noted that his estimates are for young people, and the importance of speech may become important with age, in which case his results might underestimate the long-run effects.)

If one believes Grogger’s effects are causal, then investing in the ability to not “sound black” looks to have a huge return — roughly of the same magnitude as getting one more year of schooling.

Of course, there is the issue of one’s identity. There may be personal costs associated with being black and not sounding black. But these costs would have to be pretty large. (When I have Asian Ph.D. students go on the job market in the United States, I tell them that I think there is rampant discrimination against non-English speakers and encourage them to adopt Americanized first names for the job market. Very few of my students choose to do so — either a testimony to the identity cost of pretending to be someone you aren’t, or possibly their lack of faith in my assessment of the amount of discrimination.)

I was talking with one of my colleagues about this study. He thinks it will be a very important and influential one.

My response, “Tru dat.”