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Custom-fit products require ear impressions using Sensaphonics approved techniques.
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321 IFB earphone in standard clear color
321 IFB earphone being worn, side view

321 Custom IFB Earphone

Regular price $330.00 Save $0.00
-30 in stock

The first full-isolation interruptible foldback (IFB) in-ear monitors for broadcasting, teleprompting, and security teams, the 321 provides 37 dB of broadband isolation from ambient sound, lowering the noise floor so that audio can be understood even in the noisiest environment without raising the volume. Its low profile, custom-molded design allows the 321 to fit perfectly in your ear, and the soft silicone is incredibly comfortable, even during prolonged use. With its near-invisible cable, the whole assembly is quite discreet. The 321 is available is compatible with a wide range of intercoms, and can be ordered as single (one ear) or dual-mono (two ears).

Features & Benefits

  • Designed for crew and on-air talent.
  • Low-profile custom fit with attached cable allows the earphone to disappear in the ear canal
  • Industry-leading isolation minimizes ambient sound for clearer audio at lower volumes
  • Flexible, soft silicone earpiece for a perfect fit and long-wearing comfort
  • Cable plug is compatible with all popular IFB systems including Telex, ClearCom and Comtek


  • Type: Custom-molded, ear canal-sized, single or dual-mono in-ear monitor(s)
  • Frequency Response: 200 - 6000 Hz
  • Impedance: 725 ohms @ 1kHz, 395 ohms @ 500 Hz
  • Sensitivity: 100 dB-SPL (@ 0.1V)
  • Isolation: up to 45.5 dB; broadband avg. 37 dB
  • Distortion: < 2% @ 800 Hz
  • Max Power Output: 104 dB SPL
  • Cable: Teflon, permanently attached
  • Weight: 1 ounce (approx)
  • Additional Accessories: Hard-shell Pelican case, shirt clip, cleaning tool, and pocket storage pouch.

Available Downloads

Explore these resources to help you how to safely and effectively use our products.

Instructions For Getting Your Ear Impressions

To ensure the maximum protection and quality, our in-ear monitors are custom fit to your ear. After your order is placed, please follow these steps to ensure successful delivery of your custom-fit IEM.

1. Download our detailed impression instructions

Download and print our ear impression instructions. Take the instructions with you to your audiologist appointment. The impressions must meet these specifications.


In order to get professional made ear impressions, you must schedule an appointment with an audiologist. View our list of approved audiologists or contact us.


Ship the completed ear impressions (UPS/FedEx) and a receipt of your online order (or this order form) to:

660 N. Milwaukee Avenue
Chicago, IL 60642

We'll be in touch when your in-ear monitor is ready.