What are the indicators that allow us to estmate someone's age over the phone?

I think it might have to do more with the speed of talking. Then again, people think I sound like I’m in my early 30’s.

Tone, pitch, syntax, speed of response (lack of hesitation), enunciation, etc.

I think objective tests would show that you would do no better than chance. This is just a guess, but it comes from my experience with my girlfriend, who is blind, and has a pretty bad record of guessing age and/or race in person, let alone over the phone, and her hearing is supposedly better than ours.

Ask them if they know who Arlo Guthrie is? That will narrow it down.

Vocabulary has a lot to do with this. For example, people in my age group often use the word “icebox” to refer to a refrigerator. Perhaps you are subconsciously picking up on word usage.

I’m with @CaptainHarley. Even though today’s adults are adapting to the modern lingo, vocabulary is a good indicator.

Level of formality and word usage. Frequently you can also tell race and state or area of origin.

I think it is difficult to tell the difference between someone who is 25 through to 60 or so. Much older their voice might sound more fragil, and as you mention under 25, their vocabulary might give it away, and the rhythm of their sentences. Some young people have a bazaar pause that I find annoying, I see it a lot on tv, in fact, shows like Greys Anatomy even the “older” people have that weird hesitation that I cannot really explain. Vocabulary usually gives away where they live more than age for me.

I’m a baby-boomer not too far from retirement age. Yet when I answer the phone with strangers, they often ask “Is your mother there?” There’s something ‘young’ about my voice—I have no idea what—so any generalizations fail in my case.

The only age group I feel I can guess fairly accurately are people in their 20s. I find that for many of them there is a certain indefinable intonation and word usage – not including slang. Often declarative statements will go up at the end rather than down, and phrases such as “I feel like…..” are used. I can sometimes hear an “expert” on NPR and will be quite sure they are my kids’ age because of these language tics. For other decades, such as 30s to 60s, it is not easy for me to tell.

Subject matter. If they are discussing Lady Gaga: under 25. iPhone: under 40, IRAs: 40–60. Prostates: over 55.

@worriedguy LMAO!! First, I love Lady Gaga, she gives me hope. I also talk about IRA’s and my health, but I don’t have a prostate. Still, I found your comment very funny!

@jfos
only adults think that adults are adapting to the modern lingo.

I can barely do it in person. I doubt that I could do it over the phone. Some 17-year-old lads sound like mature men. Some women in their 30’s have baby-girl voices that they don’t seem to think need improvement. Some middle-aged women sound like dry, aged crones, and some seniors speak with all the juice of their prime.

What I’m wondering is, when you think “She sounds like she’s in her 20’s/40’s/60’s,” how do you ever validate your guesses? Maybe you’re not actually pegging them right, and you’re not receiving corrective feedback. Even if you ask, how would you know if you’re getting the truth? If somebody said to me, “You sound like you’re about 35,” why wouldn’t I say, “That’s about right”?

@LeotCol That’s true.