The HTI-96-Min hydrophone is one of the most commonly used underwater sound sensors in research and fieldwork. Compact and deep-water capable, it includes a built-in preamplifier and offers solid performance without breaking the budget.
This discussion provides a concise comparison between the HTI-96 and other widely used research hydrophones, examining differences in frequency range, sensitivity, noise performance, durability, and cost. It further outlines the main scientific and engineering contexts in which the HTI-96 is employed, as well as key findings from field evaluations regarding its practical strengths and limitations.
Technical Comparison of HTI-96 vs. Other Hydrophones
Frequency Range Comparison
The HTI-96-Min exhibits a frequency response of approximately 2 Hz to 30 kHz, ideal for most ambient and biological sound measurements. In comparison, the Brüel & Kjær Type 8103 and Teledyne Reson TC4013 extend up to 180 kHz and 170 kHz, respectively—making them more suitable for high-frequency studies such as dolphin echolocation. Nevertheless, the HTI-96’s bandwidth adequately covers most marine communication and noise-monitoring needs. Some studies caution that it lacks calibration above 50 kHz but confirm negligible effect within its calibrated range.
Sensitivity and Noise Performance
Regarding sensitivity, the HTI-96 with its built-in preamplifier achieves approximately –165 dB re 1 V/µPa, comparable to Reson TC4032 at –170 dB re 1 V/µPa. Its low self-noise around 54 dB re 1 µPa/√Hz at 10 Hz allows accurate ambient noise detection. Conversely, passive models like the Reson TC4013, though extending to higher frequencies, exhibit higher self-noise at low frequencies. The HTI-96’ s user-configurable gain and filtering options add flexibility, while its internal amplification simplifies field use.
Durability and Depth Rating
The HTI-96 shows excellent durability and pressure tolerance. It is rated for depths up to 3048 m, surpassing many competitors such as Brüel & Kjær Type 8103 (~400 m), Reson TC4013 (~700 m), and TC4032 (~600 m). Its polymer-encapsulated ceramic transducer and internal shielding ensure robustness and low interference. A NOAA field report noted that Reson hydrophones were too delicate for rugged fieldwork. The same report highlighted that the HTI-96-Min’s robust design made it ideal for portable monitoring systems.
Cost and Customization
Cost-effectiveness is a key advantage: the HTI-96-Min typically costs around $800 USD, versus several thousand dollars for premium B&K or Reson units. For large-scale networks or long-term deployments, this difference significantly reduces operational risk and cost. Its customizable configuration including preamplifier gain, connector type, and cable length adds practical flexibility for researchers.
Summary Table of Key Specifications
| Feature | HTI-96-Min | Brüel & Kjær Type 8103 | Teledyne Reson TC4013 | Reson TC4032 |
| Frequency Range | 2 Hz – 30 kHz | 0.1 Hz – 180 kHz | 1 Hz – 170 kHz | 1 Hz – 120 kHz |
| Sensitivity (with preamp) | –165 dB re 1 V/µPa | –211 dB re 1 V/µPa | –211 dB re 1 V/µPa | –170 dB re 1 V/µPa |
| Self-Noise | ~54 dB re 1 µPa/√Hz @10 Hz | Very low (reference grade) | Moderate | Very low |
| Max Depth Rating | 3048 m | 400 m | 700 m | 600 m |
| Typical Cost | ~$800 | $3,000–$5,000 | $2,000–$3,000 | $3,000+ |
| Special Features | Built-in preamp, customizable | Laboratory calibration | Wide bandwidth | High accuracy preamp |
Scientific Applications of the HTI-96
- Oceanography & Environmental Monitoring: Used for ambient noise studies such as the JOMOPANS project in the North Sea (10 Hz–20 kHz). Well-suited for long-term systems tracking natural and human-made sounds like wind, waves, and shipping.
- Marine Biology: Applied to fish and marine mammal acoustics. Supports studies on fish hearing, manatee calls, and whale communication. Detects most biological sounds up to 50 kHz, serving as a cost-effective alternative for large monitoring arrays.
- Engineering & Acoustics Research: Used by the USGS to monitor sediment transport in Colorado streams, performing well under harsh conditions. In the seismic industry, embedded in ocean-bottom nodes and streamer cables due to its durability and modular design.
Real-World Field Use Cases
Field deployments confirm the HTI-96’s adaptability and reliability. In the JOMOPANS North Sea network, HTI-96-Min sensors collected continuous sound data for months under extreme marine conditions, producing results consistent with international acoustic standards.
In freshwater, the USGS deployed HTI-96-Min Exp hydrophones for month-long sediment transport studies in Halfmoon Creek, Colorado, where they endured harsh physical conditions without failure.
In wildlife monitoring, simultaneous recordings from HTI-96 and Reson hydrophones in Florida manatee habitats demonstrated comparable acoustic fidelity despite significant cost differences. Conservationists have also used HTI-96 units to monitor coral reef soundscapes and detect illegal dynamite fishing.
Conclusion
The HTI-96-Min hydrophone strikes a solid balance of performance, toughness, and affordability, making it a go-to for underwater research. Used across ocean noise, marine biology, and seismic studies, it has earned a reputation for reliability and versatility. For most projects under 30 kHz, it remains a proven, cost-effective choice.
