Interaural time difference and how to find your phone instantly 

So I was actually wearing headphones and still tilted my head around like the biggest idiot. Turns out that the time delay becomes significantly less noticeable when the source of the sound turns with you...

Dang it! Now I understand why I hear high pitch noises in wrong spots! Thanks for answering one of my sub-conscious questions!

Default tones also just don't work for people that are hard of hearing. My father in law got a new phone - claimed that it was defective because he kept missing calls. Took it back to the store, they said it was fine, etc. Finally, he brought it to me. He is standing across the room, holding the phone, I call his phone, it starts ringing nice and loud, but no reaction at all from him. I take the phone, go in to ring tones and just start making changes while I watch him. After playing a dozen or so with no reaction at all, I play one - he looks up - "You got it to ring?". Set that as his ring tone. Problem solved.

It is easier to locate high pitched sounds if your ears are further from each other. I once lived a place with a shared space with plants and we got a cicada somehow with some plants. It were driving us nuts with it's chirping, but we couldn't locate it until I held a 25 cm cardboard tube to each ear and walked around. My neighbor were laughing so hard, but still was quite impressed when I found the critter :-)

"I don't know if you can tell from the video but Django is actually a GOOD BOY."

This is content. Holy moly. I never knew how badly I wanted to know the things you just told me until you told them to me but I am very glad that you did.

"Make your phone easier to find, with science" ...oh that sounds boring. *Oh, it's a Steve Mould video!* *_Clicks_*

In music production we usually arrange sounds in the stereo field using the pan control - basically altering the balance of the amplitude between the left and right channels. But, just like this video, you can use what's called a Haas Delay instead, which alters the time relationship between left and right instead. The downside is you might run into phase cancellation issues if your stereo mix is ever collapsed into mono, what we call 'mono compatibility'.

1:00 Steve experiments science on his better half 2:00 How you detect where a sound is coming from 3:30 Why some sounds are difficult to locate 5:50 How to change the find phone tune for Android (easy) 6:00 How to change for iPhone (you can't) 7:00 How birds make use of this 7:50 Why police sirens are difficult to locate and what can be done about it 9:50 Django is a good boy! Amazing video Steve, as always - and thanks! :)

The problem with this video is the people who need it most can't watch it.

excellent video as always Steve. Keep it up!

The ambulances I heard in Paris were much easier to locate by sound than any other I've heard. They use the same siren in Morocco as well. It has two pitches that switch sharply between each other. This gives you both direction due to the inter-aural time difference at the alternation. And it gives you a sense of how fast it is coming or going because it is always the same two pitches so you can sense the Doppler effect. Sirens that smoothly rise and fall in pitch make both speed and location hard to hear.

That bit about the bird calls was super interesting! Always love your stuff! -a 3rd year mechanical engineering student

Higher pitch makes it easier to find the phone from longer distances. Which is probably more important.

I’ve found the Find My iPhone tone is great for knowing which ROOM the phone is in, but then I’m left searching for over a minute under pillows. So a mix of high pitch and white noise would be great, but hey...Apple won’t let us change it.

Change your ringtone to just shout: YOU´LL NEVER FIND ME!

When I was a kid I found it incredibly hard to locate a cricket. It's chirping and I have NO WAY of telling where the sound is coming from. Both ears work and I have excellent hearing. WTF?

i usually find it very easy to hear the cop sirens blaring behind me

The easiest sound to locate is a downward frequency sweep - a chiieeaaoouu type sound. It incorporates as much frequency range as possible, and it has more temporal precision than white noise. More distinctive too.

fun-fact. comment on 8:50 - the exact position can also be located thanks to the structure of our ears, which changes the incoming sound in different ways if it's coming from different directions. If the sound is coming from your right hemisphere, then your left ear will not change the shape of the sound wave, however, the right ear will. And once our brain lined up one signal to the other, it will look at how it was distorted to find out not only the horizontal but also the vertical angle of the incoming sound. Moreover, it does so for multiple sounds coming from different directions, which is absolutely amazing. It really blows my mind how complex is the analysis of the incoming sound, that our brain does non-stop 24/7 like nothing. UPD: dog's can't do this ear-shape-distortion-analysis, which is why they tilt their head every time.

This is one of the most interesting and multi-disciplinary youtube videos I've seen!

I can't stop laughing between 6:00 and 6:30. I played it 10 times and it's still funny.

Steve , I’m a huge fan and my son and I are binging on your channel. This is how you mix science with daily problems and that’s when people take more notice. We’ve just hidden each other’s phones and only my phone has the changed tone. Let’s do this. Btw this is helping our lockdown experience. Many thanks Steve.

This is how virtual surround sound on games and phones works for headphones! It processes the sounds with Interaural time differences and level delays. HRTF is amazing. Great video!

For low freqs, phase differences provide good cues, but not for high freqs, as explained. I'm always amazed that the brain can detect lags down to about 10 MICROseconds! However, for high freqs, intensity differences are useful, due to the head shadow effect, whereas for low freqs that doesn't work well because long wavelengths bend around. So these are somewhat complementary cues. And then there are transfer functions due to the intricate shape of the ear that leads to interference patterns, the best cue for elevation and front/back localization that doesn't require head rotation.

Finally an explanation why I can never find the ambulance. I though it was only my handicap.

I watched this yrs ago, RU-vid brought it back. I must say this, Your wife is Stunning, wow! Keep up the great videos

Steve, your presentation is so great. Love that I found this channel.

You didn't pet your good boy 0/10 video.

Love your reaction to the word "iTunes"...lol. I remember one day (long ago) importing a bunch of MP3s into itunes, then later when trying to copy them to another device I found out iTunes converted all the file names to seemingly random long stings of characters, and were no longer playable on other devices. Don't think I've bought an Apple product since.

I'm glad you covered this topic as it confirmed what I suspected to be the case. I always wandered why reversing sirens are now white noise instead of tones with a very narrow frequency band and figured this was probably why. They experimented with having narrow blasts of white noise on ambulances but it just confused people so that idea was abandoned.

Now I understand why Steve always looks so happy. Lucky guy.

I have a fax/modem sound as a ring tone, quite effective even at low volume, but now I know why it's easier to locate once the initial handshake part is over and there is basically white-noise. However I think a high pitch phase modulation is still necessary to help you distinguish white noise from background noise in the environment, so also the initial part of the sound is useful, because our mind tends to cancel white noise . The perfect ring tone would be a mix of the two (not really nice tho) I love your references to birds, we underestimate their abilities!

5:46 just an extra. That might be why modern trucks and lorries use white noise when reversing rather than beeping. Edit: should've finished the video

Great Video! Rarely do I still get surprised by educational videos on youtube but yours are somehow a lot more refreshing then the rest on here.

Thank you for sharing your research in this video, my mind was blown several times. Keep up the fantastic work. I am definitely a new subscriber.

THANKSGIVING I have always instinctively while searching for a sound, placed both hands (like elephant ears) behind my ears then turn my head until the sound is loudest. It works especially well for frequencies that are hard to find.

I've got hearing loss in one ear so determining which direction sounds are coming from can be difficult. Weirdly enough I can actually locate where sine waves are coming very quickly because the noise inputs to each ear is different so I pretty much know exactly where it's coming from so long as it is fairly loud.

I frigging love your channel. Only just discovered it. Slowly working my way through the archive.

9:33 That confused look is so funny! It's like he's asking "Steve, what the heck is that?!?"

You could also customize your ears by adding a tube and pointing it around in different places. Instead of the ear-reversing set-up, one with longer tubes that come out at the same place. This set up is also handy for locating the source of noises in particularly noisy, convoluted environments, like the engine compartment of a vehicle.

Steve, I like you and your channel. So much that I just bought one of your books for my grandson.

Anytime you want to do another video on sound, I will listen and give it a thumbs-up. This was great. Also, the links were great. Thank you!

Adorable beginning! "I'm cold" oh and the dog is such a sweetheart too!

The shape of human ears has this lovely shape to modify the relative harmonic proportion of sound vertically versus front/rear. When a sound has a sharp attack (intensity raising fast), such wave shape has many high frequency content. The Fourier analysis of AM modulation show an increase of bandwidth ; for example, a radio station emitting pure sine wave at 1 mhz (station number 100.0 on AM scale) with a modulation signal of 1 khz pure sine wave will show on a spectrometer a peek at 1000 khz with two lumps; one left at 999 khz and another right at 1001 khz. Using your radio receiver, on can hear that tone while changing the tuner frequency from 999 khz to 1001 khz, showing that this bandwidth phenomena is not a mathematical tricks ; it is real. As soon as a radio station has music or voice added, the transmitter frequency interfere with the nearby radio station with similar frequency. The louder and/or higher pitch music interfere with more distant frequencies. This bandwidth increase explains why each radio station must follow rules about the frequency of consecutive radio station. Brief, when a sound has a sharp attack, the relative amplitude of each harmonic allow us to tell the direction of sound up/down and front/rear. Combined with the precise timing difference mentioned in this video, humans detect sound direction over a complete sphere, 360 degrees in every direction. You may ask : does my dog, horse, ... has the same system? No, they rotate their hears to detect sound direction over a horizontal plane and tilt their head to rotate the plane which extends the hearing field vertically. Their system rely on the pray or predator to emit more than one sound while human know where is the sound source on the first shot. Our 360 sphere sound detection evolved when apes grew a brain so large that the ear lobes could not follow, it could not remain on top of the head. Most people devolved, losing muscle control of the ear lobes. But since our hearing system is superior, losing those muscle is really evolution. The very precise harmonic detection performed by the cochlea is as amazing as the echo location of bats. I give detail about the way it works on multiple messages on Quora. Search for "gingras cochlea" to find a few example and maybe update wikipedia page still mentioning "negative feedback" as reason for75% of cilias being motor vs 25% sensory.

Hey Steve, rusty balls guy here. Another great video, man! In my day job I design embedded control systems, and in the naughties I was leading the electronics and software development activities of a fair sized medical device corporation. One of the big changes coming through medical devices at that time was a standard for alarms (sad that I know it as EN60601-1-8). Anyway, before that, it was irritatingly common for medical devices to use high pitched pure tones from piezoelectric sounders. Cheap, and everybody was using them, so they sounded like real medical devices. But you could walk into a ward with one or two going off and using the sound you might not find which bay had the alarm until it was too late. The new standard requires complex alarm sounds, which can only be produced by a proper speaker, which contains a minimum amount of harmonic content, and defines pulse shapes and durations. It makes quite a difference to aural location. Oh, and they also should have visible alarms too (flashing lights) to augment the audible alarm. There are a whole load more requirements, but I’ll have bored you enough with that already!

I love how you investigate the most peculiar thing. Very intriguing!

After watching your videos i realise your wife is a very tolerant and special person. My wife says things like can you stop talking now!

Interestingly, to locate up and down by your ear, the most important feature your body uses is the unique anatomy of your ear. If you just attach some modeling clay in the ear auricle, you start struggling to locate the source of noise. Smartereveryday did a video on that topic as well. (Highly recommended)

Awesome video! We were making augmented reality games using audio (and no video) a couple of years back. We used earphones and mounted the phone on the head of the player to track movement. Then using these audio manipulation techniques to place sounds in a virtual overlay of the world.

Love your videos. From this one I learned a lot, not least that “consuming an API” is a thing. And that Jango is a good boy. Keep ‘em coming.

I never comment videos, but really, this one was really good! Don't know how you got an idea to do this topic, but really, amazing. Learned so much about something i never really gave much thought!

How are you so factual and educational but not annoying and pretentious? It's truly remarkable.

So kind of like how if I cross my eyes in a certain way in a tile room, the two images in my eyes will match 2 tiles together that are actually 2 different tiles?

Just found this channel now can't stop watching all of your videos .Can't find such amazing content anywhere on RU-vid!

I'm unreasonably excited about you doing a video about an interesting project with Node since that's basically what I do for a living :D

How strange, I just voip called my phone to find it, only to see a notification for this video on the screen. What a coincidence!

I hope Django has a good endorsement deal. He needs to monetize his brand if he ever wants to get 1,000 treats per video. ... Making a living on youtube is RUFF.

Wow! Didn't knew that. That's very very impressive Steve. Thanks for the video

Owls have one ear higher than the other to help locate sounds more accurately. This helps them tell front and back apart more easily and pinpoint the source. It’d probably comprise their vision a bit if they kept having to tilt their head

When I use 'find my phone' I use the ring to find the room, then find it via vibration

"I'm going to make my wife wear it and do some experiments"

Did some numerical analysis projects with sound waves in college. Got a lot of intuition on how the ear tells directions, which is why I set my tile to use the ringtone that shifts the most in frequency. Still happy that someone gives a comprehensive breakdown on this topic.

best chanel I have found on youtube! thank you steve

Natural aliasing, wow, that's amassing.

7:27 I was expecting an image of a different nature based on that description.

This was really interesting as always :) love your videos :)

I always thought the white noise on a vehicle reversing was them modifying it because the beep annoyed them. I always wondered this and never researched it. You have blown my mind, my favourite RU-vidr by far!

Dont forget the frequency response is much more important than the Phase information!

Thanks for the white noise mp3. Unfortunately, it's too quiet to use as a ring tone.

All of your videos are fascinating. Thank you.

Mind blown! Fantastic video, thank you 👍

I only have one functional ear very frustrating. I have learned to shake my head back and forth to locate sounds.

Steve Mould Thank You for the headphone warning (tinnitus here)

I actually found your video by searching clip about interaural time different for my audio tech class. This is like learning the science and applied it to real life. Thank you so much.

This explains SO MUCH! Thank you!

Gentleman, I have to thank you a lot. Your content is accurate, on point and scientifically Correct. Now I can explain phase difference and psychoacoustics to my mum with your drawings :D ahah Jokes aside, MMmany greetings from Turin, Italy :)

Hey Steve! You two are a very cute couple. Great job on the awesome videos!

That was super interesting! Thank you for making this!

You may think I'm being facetious when I call this kind of content riveting, but I enjoy it sooo much. Thank you!

Clearly, Django is a good boy, yes. Excuse me but I must just go and present some test tones to my dog, who is also a good boy.

"interoral" fuck yeah man

This was very interesting!!! Thanks for your great content:)

Very intriguing video. I can definitely apply some of these concepts immediately.

I remember those bloody horrible sirens being used in ambulance in Stafford in 1999.

"You can't... do it.. on iphone." Synopsis of everything apple.

Interesting subject. Well presented. Thumbs up.

You are a solid gold nerd, love your videos.

Steve and Brad from Bon Appetit would be a great pair to watch doing a video together. They both appreciate a Good Boy, and they're both hilarious.

Isn't it basically the same reason that trucks in the UK and europe don't make the high pitched beep when backing up anymore. It's harder to locate that, than random white noise.

It's very informative and interesting . I see this things happening around me all the time but never knew why

impecable video. thanks for your work

Look at the guy showing off his wife :P

2:04 was that a pun I ear?

Man omg, i am mezmerized! You outdone yourselve there, steve!

Mind. Blown. I'm never going to not think about this now whenever i hear a sound that throws me off.

Wow this experiment is really amazing. I have never thought of that and the way that the brain 🧠 locate sound source by aligning the signals of the two ears. Thank you !

This was a great video, thanks!

Great content! Thanks!

Everyone hates my ringtone, but it uses these tricks to make my phone easy to locate. It's the sound of a helicopter engine starting. You first get the spool up sound, which is where I usually pick up my phone and either answer or reject the call, but if I can't find it amongst the cushions, the engine lights off, and you get the pile of white noise and roaring we all associate with a turbine engine, and I can zero in on the phone rather quickly. :P