diff --git a/mhkit/acoustics/__init__.py b/mhkit/acoustics/__init__.py
index eb6857c6..f91eec6f 100644
--- a/mhkit/acoustics/__init__.py
+++ b/mhkit/acoustics/__init__.py
@@ -6,4 +6,4 @@
 """
 
 from mhkit.acoustics import io, graphics
-from .base import *
+from .analysis import *
diff --git a/mhkit/acoustics/base.py b/mhkit/acoustics/analysis.py
similarity index 99%
rename from mhkit/acoustics/base.py
rename to mhkit/acoustics/analysis.py
index 6c8a6f89..946d5580 100644
--- a/mhkit/acoustics/base.py
+++ b/mhkit/acoustics/analysis.py
@@ -75,6 +75,7 @@ def minimum_frequency(
     ---------
     Jennings 2011 - Computational Ocean Acoustics, 2nd ed.
     """
+
     # Convert water_depth to a NumPy array for vectorized operations
     water_depth = np.asarray(water_depth)
 
@@ -124,6 +125,8 @@ def sound_pressure_spectral_density(
     spsd: xarray.DataArray (time, freq)
         Spectral density [Pa^2/Hz] indexed by time and frequency
     """
+
+    # Type checks
     if not isinstance(pressure, xr.DataArray):
         raise TypeError("'pressure' must be an xarray.DataArray.")
     if not isinstance(fs, (int, float)):
@@ -367,6 +370,8 @@ def band_average(
         Frequency band-averaged sound pressure spectral density level [dB re 1 uPa^2/Hz]
         indexed by time and frequency
     """
+
+    # Type checks
     if not isinstance(spsdl, xr.DataArray):
         raise TypeError("'spsdl' must be an xarray.DataArray.")
     if not isinstance(octave, int):
@@ -618,6 +623,7 @@ def _band_sound_pressure_level(
     out: xarray.DataArray (time, freq_bins)
         Sound pressure level [dB re 1 uPa] indexed by time and frequency of specified bandwidth
     """
+
     # Type checks
     if not isinstance(spsd, xr.DataArray):
         raise TypeError("'spsd' must be an xarray.DataArray.")
@@ -703,6 +709,7 @@ def third_octave_sound_pressure_level(
     mspl: xarray.DataArray (time, freq_bins)
         Sound pressure level [dB re 1 uPa] indexed by time and third octave bands
     """
+
     # Type checks
     if not isinstance(spsd, xr.DataArray):
         raise TypeError("'spsd' must be an xarray.DataArray.")
@@ -761,6 +768,7 @@ def decidecade_sound_pressure_level(
     mspl : xarray.DataArray (time, freq_bins)
         Sound pressure level [dB re 1 uPa] indexed by time and third octave bands
     """
+
     # Type checks
     if not isinstance(spsd, xr.DataArray):
         raise TypeError("'spsd' must be an xarray.DataArray.")
diff --git a/mhkit/acoustics/graphics.py b/mhkit/acoustics/graphics.py
index 73b03f5c..4cc28d91 100644
--- a/mhkit/acoustics/graphics.py
+++ b/mhkit/acoustics/graphics.py
@@ -5,7 +5,7 @@
 """
 
 import matplotlib.pyplot as plt
-from .base import _fmax_warning
+from .analysis import _fmax_warning
 
 
 def plot_spectogram(spsdl, fmin=10, fmax=100000, fig=None, ax=None, **kwargs):
diff --git a/mhkit/acoustics/io.py b/mhkit/acoustics/io.py
index a626fadd..d33df056 100644
--- a/mhkit/acoustics/io.py
+++ b/mhkit/acoustics/io.py
@@ -122,7 +122,7 @@ def _calculate_voltage_and_time(
     raw_voltage = raw.astype(float) / max_count * peak_voltage
 
     # Get time
-    end_time = np.datetime64(start_time) + np.timedelta64(length, "s")
+    end_time = np.datetime64(start_time) + np.timedelta64(length * 1000, "ms")
     time = pd.date_range(start_time, end_time, raw.size + 1)
 
     return raw_voltage, time, max_count
diff --git a/mhkit/dolfyn/adv/clean.py b/mhkit/dolfyn/adv/clean.py
index bf91efac..69a03587 100644
--- a/mhkit/dolfyn/adv/clean.py
+++ b/mhkit/dolfyn/adv/clean.py
@@ -6,7 +6,6 @@
 from ..velocity import VelBinner
 from ..tools.misc import group, slice1d_along_axis
 
-warnings.simplefilter("ignore", np.exceptions.RankWarning)
 
 sin = np.sin
 cos = np.cos
diff --git a/mhkit/tests/acoustics/test_analysis.py b/mhkit/tests/acoustics/test_analysis.py
index e6a4959b..fa861cba 100644
--- a/mhkit/tests/acoustics/test_analysis.py
+++ b/mhkit/tests/acoustics/test_analysis.py
@@ -237,7 +237,7 @@ def test_fmax_warning(self):
         """
         Test that fmax warning adjusts the maximum frequency if necessary.
         """
-        from mhkit.acoustics.base import _fmax_warning
+        from mhkit.acoustics.analysis import _fmax_warning
 
         # Test case where fmax is greater than Nyquist frequency
         fn = 1000
@@ -260,7 +260,7 @@ def test_validate_method(self):
         """
         Test the validation of the 'method' parameter in band_average or time_average.
         """
-        from mhkit.acoustics.base import _validate_method
+        from mhkit.acoustics.analysis import _validate_method
 
         # Valid method string
         method_name, method_arg = _validate_method("median")