• Log #2: Measurement Setup & Reference Conditions

    hide-key • 01/03/2026 at 20:12 • 0 comments

    This log documents the measurement setup and reference conditions used in the following observations.

    Note: In the first part of the video, the exciter itself is intentionally damped by direct finger contact.
    This is shown only as a reference to demonstrate that the system still behaves like a normal exciter-driven object at the drive point.

    The remainder of the video and all following observations focus on the behavior of the shell itself under different contact conditions.

    Following the unexpected robustness observed during hand-held listening tests, I decided to introduce simple, repeatable measurements to establish reference conditions. The goal was not precision acoustics, but consistency: to compare relative changes under different physical constraints using the same setup.

    Measurements were performed using a smartphone-based spectrum analyzer app (Sonic Tools SVM), capturing frequency response trends rather than absolute sound pressure values.

    The exciter position was kept fixed throughout all tests. Only the external boundary conditions of the shell were varied.

    A reference condition was first defined:

    Reference: Near Free-standing Condition

    The shell was supported by a custom-made minimal contact stand (three-point support), designed to approximate a free-standing state while remaining physically stable.

    This reference revealed a distinct low-frequency emphasis (approximately 50-100 Hz), forming a baseline profile for comparison.

    Subsequent measurements intentionally avoided changing input signal level, exciter mounting, or shell orientation, focusing solely on how external interaction affected the vibrational behavior.

    At this stage, the measurements serve as qualitative evidence supporting the initial listening observations, not as laboratory-grade acoustic data.

  • Log #1: The Unexpected Observation

    hide-key • 01/03/2026 at 20:06 • 0 comments

    Full build details are available on Instructables.

    Context: A Shift From Building to Observation

    This project began as a hands-on maker experiment: building a haptic speaker using a Nautilus shell.

    During early testing, however, the focus shifted. Unexpected acoustic and vibrational behaviors emerged that could not be explained by conventional speaker design alone.

    At that point, the project transitioned from a simple build log into an observational and analytical exploration.

    — Observation —

    This project began as a deliberately low-expectation experiment: to see what kind of “cheap sound” could be produced by attaching an exciter to a real Nautilus shell.

    During early listening tests, however, an unexpected behavior became apparent.

    When the shell was held by hand—regardless of where it was touched or gripped (inner whorl, middle region, or outer shell)—there was no clearly audible change in sound pressure, tonal balance, or perceived vibration intensity.

    This was surprising. In most small speakers or resonant objects, direct hand contact strongly damps vibration, altering both loudness and frequency response. Human tissue typically acts as a strong mechanical absorber.

    Yet in this case, even firm gripping did not produce an obvious acoustic change by ear.

    This observation was repeated multiple times and was consistent enough to raise a question:

    Why does the Nautilus shell appear unusually insensitive to external damping by touch?

    At this stage, no claim is made about optimality or biological intent. This log simply documents an observation that contradicts common expectations in small-scale vibration systems and motivated further measurement and comparison tests.