How to Measure Your IEM’s Frequency Response Graph – Affordable, Portable, Accurate, and Repeatable.

Ear simulators are important tools used for calibrating earphones, and they mimic the occlusion effect, which occurs when an ear canal is filled by a foreign object, resulting in a hollow or booming sound. To achieve consistent and reliable measurements, it is crucial to use standardized devices.

However, industry-standard occluded-ear simulators can be expensive for average consumers. This article explores an affordable alternative to create IEM measurements, inspired by the setup used by In-Ear Fidelity’s measurement database.

Hardware Requirements

To make IEM measurements, you’ll need the following hardware:

1. Occluded-Ear Simulator Coupler (IEC 60318-4 Compliant): This specialized inner ear simulator can be purchased from Taobao, a Chinese e-commerce website.
2. 3.5mm Headphone/Microphone Splitter Cable Adapter: This inexpensive adapter can be easily found on Amazon.
3. Apple Lightning to 3.5mm Headphone Adapter: An adapter to connect your iOS device to the splitter cable.

Purchasing the Occluded-Ear Simulator

Buying the occluded-ear simulator from Taobao might seem complicated at first, but using a third-party shopping and shipping agent, like Superbuy, can simplify the process. You’ll order the product through Superbuy, and they will handle the purchase from Taobao and ship it to you securely.

Software Requirements

For IEM measurements, the following software is recommended:

1. iOS AudioTools: Use periodic noise averaging or sine sweep peak holding for portable measurements on iOS devices.
2. Room EQ Wizard (REW): Ideal for desktop measurements and occasional use of ARTA, depending on specific functions needed.

Understanding Limitations

It’s important to be aware of the limitations of the occluded-ear simulator:

1. Individual Ear Variations: Results may vary due to different ear characteristics.
2. Leakage Not Simulated: The simulator does not account for leakage between earmoulds and the ear canal.
3. Low and High Frequencies: Results may deviate from real ear performance, especially at low frequencies (below 100 Hz) and high frequencies (above 10 kHz).

Conclusion

Creating IEM measurements with an affordable occluded-ear simulator can provide consistent and comparable results. While it may not perfectly mimic a human ear, this setup offers a cost-effective alternative for those interested in headphone measurements. Understanding the limitations and potential variations w