Dr. Andrew Huberman, Ph.D. is a Professor of Neurobiology and Ophthalmology at Stanford University School of Medicine. His lab focuses on neural regeneration, neuroplasticity, and brain states such as stress, focus, fear, and optimal performance.
In this episode of Huberman Lab, Dr. Huberman breaks down the mechanism of hearing and making sense of sounds as well as things that can go wrong with hearing. He also discusses ways to accelerate learning using sound and the mechanics of our ears.
Host: Andrew Huberman (@hubermanlab)
The technical name of the ear is pinna
Ear size changes across lifespan and is an indication of how fast you are aging
Ears amplify high and low frequency sounds
Soundwaves (fluctuations in the way air is moving) are captured by ears, eardrum, and hammer
The cochlea (snail shaped structure) in ear is where soundwaves get converted to something brain can understand
Cochlea separates low frequency from high frequency
Soundwaves come in, eardrum moves on hammer, hammer bangs on cochlea and separate types of sound for processing by brain
There are many stations in which auditory information is processed before it becomes something we understand
Our brain is not only processing what the sound is, but also where it is coming from
Auditory and visual system collaborate to understand where things are taking place in space
Ventriloquism effect: you think a sound is coming from location that it’s not
Inter-oral time difference: stations in brain calculate time of arrival in left ear versus right to help understand what direction sound is coming from
The shape of your ear modifies sound depending on where it is coming from
Auto-acoustic emissions: sounds cast out by ears, not heard by the person making the sound
70% of people make noises with their ears
Certain combinations of hormones during develop are likely shaping hearing and processing
Heterosexual women have a higher rate of auto-acoustic emissions
Homosexual or bisexual women have a lower rate of auto-acoustic emissions
Binaural beats: playing one sound in one ear and a different sound in the other ear
Binaural beats place the brain into a state that is better for learning
Some dentists offer binaural beats for improved relaxation
Binaural beats have been shown to increase cognition, relaxation, creativity, pain reduction, anxiety reduction
Good evidence supporting the use of binaural beats for anxiety reduction (particularly delta, theta, alpha)
Apps have been created which will create sounds based on desired outcome – e.g., relaxation, anti-anxiety, sleep, etc.
Binaural soundwaves from lowest to highest frequency:
Delta waves (low frequency sounds) can help transition to sleep and staying asleep
Theta waves can assist with non-sleep rest – good for meditation
Alpha waves can increase alertness – great for recall of existing information
Beta waves are great for bringing the brain into focus for complex learning
Gamma waves are good for learning and problem solving
You need to be in highly alert state to bring new information in – higher soundwaves stimulate advanced learning
Low frequency waves put the brain into a relaxed state versus high frequency soundwaves which put the brain into more alert states
Possibly because we can channel focus better with background noise
White noise has been shown to enhance brain wave states for learning in adults – but – possibly detrimental in young children and infants
White noise at low intensity can enhance learning
White noise may modulate activity in regions of the brain, including dopaminergic pathway (area of the brain involved in motivation, reward)
White noise can raise base levels of dopamine released
Sounds in environment can increase learning through dopamine
Tip: if using headphones, keep particularly low because the brain is perceiving the sound to come from your head which can be stimulating
There is data that white noise can be detrimental to mapping of auditory system of brain in children
Not worth the risk of using white noise machine to help infants and children sleep through the night
Cocktail party effect: in an environment rich with sounds, you need to pay attention to certain sounds (and people) and not others
The brain is good at extracting information we need and ignoring the rest, but it takes a lot of energy
Much like we can expand visual field, we can expand and contract auditory field – actively tune out background noise or chatter
Train your hearing: disengage auditory system when you don’t need to focus on something particular
To improve auditory learning: deliberately pay attention to onset and offset of words – for example, the “J” and “f” sounds in Jeff when someone introduces themselves by name
Passively listening does not allow brain to process information and commit to memory
Listen for particular cues within speech and sound to change neurocircuitry in brain
Highlight certain words or frequency of sound to improve learning
Balance starts in the ears
Three planes head can move along: pitch (nod up and down), yan (shake side to side), roll (tilt side to side)
Depending on what direction the head is moving, different signal is sent to brain
Vestibular system works with visual system
Try moving your head fast then slow and notice the difference in difficulty and discomfort
Mechanisms in inner ear tell eyes where to go then eyes tell balance system how to function
It’s hard to balance with eyes closed because information about visual world feeds back into vestibular system
To optimize balance: raise one leg and look off short distance and gradually increase gaze – then bring gaze back in closer
Tip 1 to enhance balance: combine changes in visual environment while stationary (i.e., standing on one leg)
Tip 2 to enhance balance: look at one thing and change body posture
Vestibular system cares about acceleration – what direction you are moving and how fast
One of the best ways to cultivate a better sense of balance is to get into modes we are accelerating forward and tilted– such as skateboard, snowboard, surfboard, lean into turn on bike
Tilt the body and the head with respect to earth’s gravitational pull
Learning and ability to learn is enhanced in periods after these modes of exercise
Doppler effect: the way we are experiencing sound when the thing making the sound is moving
Firetruck, police, and ambulance sirens are a good example of Doppler
We experience sounds closer to us at higher frequency and sounds that are further away at lower frequency
Doppler effect is one of the main ways we assess what direction, speed, and trajectory sound is coming from
Bats navigate world mostly by making sound and Doppler to communicate
Tinnitus is subject to context and can vary throughout time of day, environment, sleep and even stress
Tinnitus can be caused by disruption to hair cells in the ears
Ginkgo biloba seems particularly beneficial in age-related tinnitus
Being dizzy and lightheaded have to be differentiated
Dizzy: if the world is spinning but you can focus on thumb
Lightheaded: if you feel like you’re falling or need to get on the ground
Some causes of lightheadedness: dehydrated, low in electrolytes, low blood sugar – try adding a little salt to water
To help with nausea, sea sickness, motion sickness: track eyes with the direction you are moving
The ears grow throughout your life
Biological age can be measured according to ear size – circumference of outer ears (both) in millimeters then take the average and subtract 88.1 x 1.96
Biological age = average of circumference of both ears in millimeters – 88.1 x 1.96
Loud sounds and loud environment will eventually lead to hearing loss
Avoid big inflections of sounds above what you have to endure – for example, controlling soundboard at a concert then adding in fireworks
To learn a new skill, you have to practice and get many repetitions
Taking rest within the learning block is also important – e.g., do nothing (not even look at phone) for 10 seconds between reps
Rest ties learning and improvement of skill to underlying improvement of neuron
Hippocampus and cortex are active during rest and processing repetition at 20x the speed
The brain is willing to give us the learning we want as long as we also let it rest