Final Eartell production in action
I connected the eartell product and collected data from 5 different microphones, I passed sound from various angles and at various heights and collected the data, I found that the average ITD between the amplifiers in 0.12 and the ITD from end to end microphones is 0.6msec, I converted the analog signal into sound pressure level db using a standard formula now based on the sound source and the sound signal it received my custom program will automatically adjust the ITD and mix it. I still need to add the mixer circuit which will be part of the end product.
- Published in Technology
Finalizing and securing microphones
Final Product: After lot of thinking and trying I ended up using the clips tied with zip on one side inserted into a bone conduction headphones, it does capture the sound now from all directions and the data is retrieved for a mixer circuit, The data is then extracted as a file and manipulated using audacity software. After multiple iterations of the sound recording and mixing, I am able to find the perfect spot for the TDOA.
- Published in Technology
From Patent Drawing To Reality
Assembling 5 Mic’s to a processor:
Assembling all the mic’s into one processor so that the processor can modify the signals based on the need and then mix into one output to relay into the other ear through bone conduction headphones.
- Published in Technology
Mixing audio signals from 5 different mic receivers
Mixing Audio signals from 5 mic’s:
I am placing the mic’s in 5 different angles so that they cover the sound signals from all 5 directions, left and right ear, left and right head curvature, one in the center back of the head.
Mix Sound signals after editing to adjust ITD:
All the 5 mic’s capture the sound and the sound signal is mixed into one audio source, once it is mixed into one audio source it becomes mono and it is difficult to adjust the sound based on the ITD and direction of the sound.
Mix Sound signals before editing to adjust ITD:
All these capture the sound signal and the sound signal will be modified based on the proprietary algorithm. Once the final signal is available it will be outputted into a single audio. Processor knows the source and direction of the sound, it can calculate the time difference, sound pressure and intensity for the same frequency from each of the audio signal. Hence I decided to adjust the sound signals and then mix into one for transmission through bone conduction.
- Published in Technology
Testing Interaural Time Delay
Interaural Time Delay:
The interaural time difference (or ITD) when concerning humans or animals, is the difference in arrival time of a sound between two ears. It is important in the localization of sounds, as it provides a cue to the direction or angle of the sound source from the head. If a signal arrives at the head from one side, the signal has further to travel to reach the far ear than the near ear. This pathlength difference results in a time difference between the sound’s arrivals at the ears, which is detected and aids the process of identifying the direction of sound source.
Calculating ITD using a mannequin head, But the results vary based on the obstruction object. So the values that are calculated using mannequin head might not be exact as a human tissue but we can estimate based on the angle of sound, direction and sound pressure.
- Published in Technology
Bone Conduction
Bone Conduction
Bone Conduction is the conduction of sound to the inner ear through the bones of the skull. Bone conduction transmission can be used with individuals with normal or impaired hearing.
What’s the difference between Bone conduction headphones and normal headphones?
Bone conduction is a way of conducting sound by sending the sound into a different frequency of mechanical vibration. Sent through the human skull, bone labyrinth, inner ear lymph fluid transmission, screw, auditory nerve and auditory center to transmit sound waves. In contrast to the classical sound transmission of sound waves through the diaphragm, the bone conduction eliminates many acoustic transmission steps to achieve a clear sound reduction in a noisy environment, and the sound waves won’t affect others.
When we eat a biscuit, we can hear the sound of biscuits broken because the vibration through our teeth and skulls to our inner ear. In the 18th century, the principle of bone conduction helped the great beloved deaf composer Beethoven to hear the wonderful music. Beethoven tried a technique invented by Giovanni Phillipo, England. Where he could hear the music from the jaw bones with a stick connected to the piano. This was actually the early beginning application of the bone conduction principle.
Bone conduction technology is mainly used for military, police professional headphones. Also in hearing aids, sports headphones and other fields.
- Published in Research Work
Hearing Loss
Hearing Loss:
There is no treatment, surgical or otherwise, for hearing loss due to the most common causes (age, noise, and genetic defects). For a few specific conditions, surgical intervention can provide a remedy:
- surgical correction of superior canal dehiscence
- Myringotomy, surgical insertion of drainage ventilation tubes in the tympanic membrane. Such placement is usually temporary until the underlying pathology (infection or other inflammation) can be resolved.
- radiotherapy or surgical excision of vestibular schwannoma or acoustic neuroma, though, in most cases, it is unlikely that hearing will be preserved
- Stapedectomy and stapedotomy for otosclerosis – replacement or reshaping of the stapes bone of the middle ear can restore hearing in cases of conductive hearing loss
Surgical and implantable hearing aids are an alternative to conventional external hearing aids. If the ear is dry and not infected, an air conduction aid could be tried; if the ear is draining, a direct bone condition hearing aid is often the best solution. If the conductive part of the hearing loss is more than 30–35 dB, an air conduction device could have problems overcoming this gap. A bone-anchored hearing aid could, in this situation, be a good option. The active bone conduction hearing implant Bonebridge is also an option. This implant is invisible under the intact skin and therefore minimises the risk of skin irritations.
Cochlear implants improve outcomes in people with hearing loss in either one or both ears. They work by artificial stimulation of the cochlear nerve by providing an electric impulse substitution for the firing of hair cells. They are expensive, and require programming along with extensive training for effectiveness.
Cochlear implants as well as bone conduction implants can help with single sided deafness. Middle ear implants or bone conduction implants can help with conductive hearing loss.
People with cochlear implants are at a higher risk for bacterial meningitis. Thus, meningitis vaccination is recommended. People who have hearing loss, especially those who develop a hearing problem in childhood or old age, may need support and technical adaptations as part of the rehabilitation process. Recent research shows variations in efficacy but some studies show that if implanted at a very young age, some profoundly impaired children can acquire effective hearing and speech, particularly if supported by appropriate rehabilitation.
- Published in Research Work
Adding bluetooth to the project
Adding a new I2c bluetooth receiver:
Purchased HM10 bluetooth master/slave module and connected to the board I2C pins for transfering the audio to another bluetooth paired device. Since there is no audio codec in the device it cannot really transfer the sound. but it can send the audio data received from A0 and A3 pins through the bluetooth transmitter.
- Published in Technology
Connecting multiple microphones to a single processor
Connected multiple microphones to the IO Expansion board with arduino nano processor inside. Changed the program to read the values from multiple microphones and I noticed that there is a difference of 4 db in sound when we speak onto either direction. If we speak into right left side microphone shows value of 4db less than right and vice versa.
Microphones are connected to the bone conducting headphones to simulate human head.
New Arduino Sketch that reads input from two microphones.
//size of the window
const int inputWindow = 100;
// placeholder for a single measurement
unsigned int inputSample1;
unsigned int inputSample2;
void setup() {
// initializing the analog input
//pinMode(inputPin, INPUT);
// initializing the serial communication
Serial.begin(9600);
}
void loop() {
// two variables for minimum and maximum values in window
unsigned int inputMax1 = 0;
unsigned int inputMin1 = 1024;
unsigned int inputMax2 = 0;
unsigned int inputMin2 = 1024;
// loop for the window
for (unsigned int i = 0; i < inputWindow; i++) {
// read in a single value
inputSample1 = analogRead(A0);
inputSample2 = analogRead(A3);
// get the minimum and maximum value
inputMin1 = min(inputMin1, inputSample1);
inputMax1 = max(inputMax1, inputSample1);
inputMin2 = min(inputMin2, inputSample2);
inputMax2 = max(inputMax2, inputSample2);
}
// send the values on serial
Serial.print(“Min Mic 1 : “);
Serial.print(inputMin1);
Serial.print(” Max Mic 1 : “);
Serial.print(inputMax1);
Serial.print(” Diff Mic 1 :”);
Serial.print(inputMax1 – inputMin1);
Serial.println();
Serial.print(“Min Mic 2 : “);
Serial.print(inputMin2);
Serial.print(” Max Mic 2 : “);
Serial.print(inputMax2);
Serial.print(” Diff Mic 2 :”);
Serial.print(inputMax2 – inputMin2);
Serial.println();
}
- Published in Technology
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