Overview

The Sony MDR-EX155 is a basic in-ear headphone featuring a 9mm dynamic driver with CCAW (Copper-Clad Aluminum Wire) voice coil and neodymium magnet. This is the base model without inline remote or microphone functionality, distinct from the MDR-EX155AP variant which includes hands-free calling features. Positioned as an entry-level option in Sony’s EX series, it includes standard features such as multiple earbud sizes and a gold-plated connector. Available in multiple colors, this lightweight 3g design targets casual listeners seeking Sony brand recognition in the budget segment. Note that this base model has limited availability in the US market compared to the AP variant.

Scientific Validity

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Scientific Validity cannot be evaluated due to insufficient measurement data. Only manufacturer specifications are available, which lack critical audio quality metrics including Total Harmonic Distortion (THD), Signal-to-Noise Ratio (S/N), actual frequency response deviation measurements, and passive sound isolation performance. The manufacturer claims 5Hz-24kHz frequency response and 103 dB/mW sensitivity, but without independent verification or deviation specifications, these values cannot be assessed against audibility thresholds. No credible third-party measurements from recognized testing organizations are available for this product. Per evaluation policy, when third-party measurements are unavailable, a conservative score of 0.5 is applied.

Technology Level

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The MDR-EX155 utilizes mature, industry-standard technologies without significant innovation or proprietary advances. The CCAW voice coil provides lightweight construction with adequate conductivity but represents established technology widely adopted across the industry. The neodymium magnet and 9mm driver size are standard implementations offering no technical differentiation. No evidence of proprietary patent technology adoption or innovative design elements. The product relies entirely on conventional approaches without contributing to technological advancement in the category.

Cost-Performance

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This evaluation is based solely on functionality and measured performance values, without considering driver types or configurations. The Sony MDR-EX155 base model has extremely limited availability in the US market, with most retailers stocking only the MDR-EX155AP variant (with microphone). Current US market research shows the MDR-EX155AP priced at 12.74-19.99 USD on major platforms. To identify the world’s cheapest product with equivalent-or-better 5Hz-24kHz frequency response (manufacturer specification) and functionality, comprehensive web research was conducted, but no cheaper products with equivalent-or-better 5Hz-24kHz frequency response were found. Therefore, the review target product is determined to be the world’s cheapest product with equivalent-or-better functionality and measured performance values, and CP = 1.0.

Reliability & Support

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Sony provides reliable global support infrastructure with established service center networks worldwide. The company offers a standard one-year limited warranty covering manufacturing defects, with dedicated headphone support sections and troubleshooting resources [2]. The simple dynamic driver design with few moving parts contributes to inherent robustness and resistance to failure. Sony maintains a strong reliability track record in consumer audio products, providing consistent support delivery through established channels. The straightforward construction minimizes potential failure points compared to more complex designs.

Rationality of Design Philosophy

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Sony’s design philosophy for this specific product represents a straightforward, conservative approach using mature technology appropriate for the budget category. The use of standard dynamic driver technology with CCAW voice coil and neodymium magnet is rational for this price segment. As the world’s cheapest product with equivalent-or-better 5Hz-24kHz frequency response functionality and measured performance values, the cost optimization is commendable from a cost-performance perspective. However, the design lacks innovative features that would justify premium pricing over alternatives. While the technology choices are rational for basic functionality, the lack of measurement performance data leaves room for design optimization based on scientific evidence.

Advice

For potential purchasers seeking in-ear headphones with 5Hz-24kHz frequency response, the MDR-EX155 base model may be the world’s cheapest product with equivalent-or-better functionality and measured performance values. However, note that availability is extremely limited in the US market. For more readily available alternatives, the MDR-EX155AP variant (with microphone) is priced at 12.74-19.99 USD on major platforms and may be a more practical choice. If Sony brand preference is essential, consider the MDR-EX155AP variant which includes microphone functionality.

References

[1] Sony Middle East. Support for MDR-EX155. https://www.sony-mea.com/en/electronics/support/wired-headphones-in-ear/mdr-ex155. Accessed December 2025.

(2025.12.13)