diff --git a/pyrasa/irasa.py b/pyrasa/irasa.py
index 6780d48..49a970b 100644
--- a/pyrasa/irasa.py
+++ b/pyrasa/irasa.py
@@ -1,11 +1,10 @@
 import fractions
 from collections.abc import Callable
+from typing import TYPE_CHECKING, Any
 
 import numpy as np
 import scipy.signal as dsp
 
-from pyrasa.utils.input_classes import IrasaKwargsTyped, IrasaSprintKwargsTyped
-
 # from scipy.stats.mstats import gmean
 from pyrasa.utils.irasa_utils import (
     _check_irasa_settings,
@@ -13,6 +12,10 @@
     _compute_sgramm,
     _crop_data,  # _find_nearest, _gen_time_from_sft, _get_windows,
 )
+from pyrasa.utils.types import IrasaFun
+
+if TYPE_CHECKING:
+    from pyrasa.utils.input_classes import IrasaSprintKwargsTyped
 
 
 # TODO: Port to Cython
@@ -20,9 +23,8 @@ def _gen_irasa(
     data: np.ndarray,
     orig_spectrum: np.ndarray,
     fs: int,
-    irasa_fun: Callable,
+    irasa_fun: IrasaFun,
     hset: np.ndarray,
-    irasa_kwargs: dict | IrasaKwargsTyped | IrasaSprintKwargsTyped,
     time: np.ndarray | None = None,
 ) -> tuple[np.ndarray, np.ndarray, np.ndarray]:
     """
@@ -45,12 +47,8 @@ def _gen_irasa(
         data_down = dsp.resample_poly(data, down, up, axis=-1)
 
         # Calculate an up/downsampled version of the PSD using same params as original
-        irasa_kwargs['h'] = h
-        irasa_kwargs['time_orig'] = time
-        irasa_kwargs['up_down'] = 'up'
-        spectrum_up = irasa_fun(data_up, int(fs * h), spectrum_only=True, **irasa_kwargs)
-        irasa_kwargs['up_down'] = 'down'
-        spectrum_dw = irasa_fun(data_down, int(fs / h), spectrum_only=True, **irasa_kwargs)
+        spectrum_up = irasa_fun(data=data_up, fs=int(fs * h), h=h, time_orig=time, up_down='up')
+        spectrum_dw = irasa_fun(data=data_down, fs=int(fs / h), h=h, time_orig=time, up_down='down')
 
         # geometric mean between up and downsampled
         # be aware of the input dimensions
@@ -153,26 +151,34 @@ def irasa(
         'eigenvalue_weighting': dpss_eigenvalue_weighting,
     }
 
-    irasa_kwargs: IrasaKwargsTyped = {
-        'nperseg': psd_kwargs.get('nperseg'),
-        'noverlap': psd_kwargs.get('noverlap'),
-        'nfft': psd_kwargs.get('nfft'),
-        'h': None,
-        'up_down': None,
-        'time_orig': None,
-        'dpss_settings': dpss_settings,
-        'win_kwargs': win_kwargs,
-    }
-
-    freq, psd = _compute_psd_welch(data, fs=fs, **irasa_kwargs)
+    def _local_irasa_fun(
+        data: np.ndarray,
+        fs: int,
+        *args: Any,
+        **kwargs: Any,
+    ) -> np.ndarray:
+        return _compute_psd_welch(
+            data,
+            fs=fs,
+            nperseg=psd_kwargs.get('nperseg'),
+            win_kwargs=win_kwargs,
+            dpss_settings=dpss_settings,
+            noverlap=psd_kwargs.get('noverlap'),
+            nfft=psd_kwargs.get('nfft'),
+        )[1]
+
+    freq, psd = _compute_psd_welch(
+        data,
+        fs=fs,
+        nperseg=psd_kwargs.get('nperseg'),
+        win_kwargs=win_kwargs,
+        dpss_settings=dpss_settings,
+        noverlap=psd_kwargs.get('noverlap'),
+        nfft=psd_kwargs.get('nfft'),
+    )
 
     psd, psd_aperiodic, psd_periodic = _gen_irasa(
-        data=np.squeeze(data),
-        orig_spectrum=psd,
-        fs=fs,
-        irasa_fun=_compute_psd_welch,
-        hset=hset,
-        irasa_kwargs=irasa_kwargs,
+        data=np.squeeze(data), orig_spectrum=psd, fs=fs, irasa_fun=_local_irasa_fun, hset=hset
     )
 
     freq, psd_aperiodic, psd_periodic = _crop_data(band, freq, psd_aperiodic, psd_periodic, axis=-1)
@@ -296,13 +302,19 @@ def irasa_sprint(  # noqa PLR0915 C901
         'mfft': mfft,
         'hop': hop,
         'win_duration': win_duration,
-        'h': None,
-        'up_down': None,
         'dpss_settings': dpss_settings,
         'win_kwargs': win_kwargs,
-        'time_orig': None,
     }
 
+    def _local_irasa_fun(
+        data: np.ndarray,
+        fs: int,
+        h: int | None,
+        up_down: str | None,
+        time_orig: np.ndarray | None = None,
+    ) -> np.ndarray:
+        return _compute_sgramm(data, fs, h=h, up_down=up_down, time_orig=time_orig, **irasa_kwargs)[2]
+
     # get time and frequency info
     freq, time, sgramm = _compute_sgramm(data, fs, **irasa_kwargs)
 
@@ -310,9 +322,8 @@ def irasa_sprint(  # noqa PLR0915 C901
         data=data,
         orig_spectrum=sgramm,
         fs=fs,
-        irasa_fun=_compute_sgramm,
+        irasa_fun=_local_irasa_fun,
         hset=hset,
-        irasa_kwargs=dict(irasa_kwargs),
         time=time,
     )
 
diff --git a/pyrasa/utils/input_classes.py b/pyrasa/utils/input_classes.py
index 27e7b0f..4090853 100644
--- a/pyrasa/utils/input_classes.py
+++ b/pyrasa/utils/input_classes.py
@@ -1,27 +1,11 @@
 from typing import TypedDict
 
-import numpy as np
-
-
-class IrasaKwargsTyped(TypedDict):
-    nperseg: int | None
-    noverlap: int | None
-    nfft: int | None
-    h: int | None
-    time_orig: None | np.ndarray
-    up_down: str | None
-    dpss_settings: dict
-    win_kwargs: dict
-
 
 class IrasaSprintKwargsTyped(TypedDict):
     mfft: int
     hop: int
     win_duration: float
-    h: int | None
-    up_down: str | None
     dpss_settings: dict
     win_kwargs: dict
-    time_orig: None | np.ndarray
     # smooth: bool
     # n_avgs: list
diff --git a/pyrasa/utils/irasa_utils.py b/pyrasa/utils/irasa_utils.py
index 9f73cd5..830bcf2 100644
--- a/pyrasa/utils/irasa_utils.py
+++ b/pyrasa/utils/irasa_utils.py
@@ -137,10 +137,6 @@ def _compute_psd_welch(
     scaling: str = 'density',
     axis: int = -1,
     average: str = 'mean',
-    up_down: str | None = None,
-    spectrum_only: bool = False,
-    h: float | None = None,
-    time_orig: np.ndarray | None = None,
 ) -> tuple[np.ndarray, np.ndarray]:
     """Function to compute power spectral densities using welchs method"""
 
@@ -171,10 +167,7 @@ def _compute_psd_welch(
         weighted_psds = [ratios[ix] * cur_sgramm for ix, cur_sgramm in enumerate(psds)]
         psd = np.sum(weighted_psds, axis=0) / np.sum(ratios)
 
-    if spectrum_only:
-        return psd
-    else:
-        return freq, psd
+    return freq, psd
 
 
 def _compute_sgramm(  # noqa C901
@@ -188,8 +181,7 @@ def _compute_sgramm(  # noqa C901
     up_down: str | None = None,
     h: int | None = None,
     time_orig: np.ndarray | None = None,
-    spectrum_only: bool = False,
-) -> tuple[np.ndarray, np.ndarray, np.ndarray] | np.ndarray:
+) -> tuple[np.ndarray, np.ndarray, np.ndarray]:
     """Function to compute spectrograms"""
 
     if h is None:
@@ -231,7 +223,4 @@ def _compute_sgramm(  # noqa C901
 
     sgramm = np.squeeze(sgramm)  # bring in proper format
 
-    if spectrum_only:
-        return sgramm
-    else:
-        return freq, time, sgramm
+    return freq, time, sgramm
diff --git a/pyrasa/utils/types.py b/pyrasa/utils/types.py
new file mode 100644
index 0000000..a4dd657
--- /dev/null
+++ b/pyrasa/utils/types.py
@@ -0,0 +1,9 @@
+from typing import Protocol
+
+import numpy as np
+
+
+class IrasaFun(Protocol):
+    def __call__(
+        self, data: np.ndarray, fs: int, h: int | None, up_down: str | None, time_orig: np.ndarray | None = None
+    ) -> np.ndarray: ...