diff --git a/leaf/Inc/leaf-physical.h b/leaf/Inc/leaf-physical.h
index 66cbf31..d0289c5 100644
--- a/leaf/Inc/leaf-physical.h
+++ b/leaf/Inc/leaf-physical.h
@@ -1260,7 +1260,71 @@ typedef struct _tStiffString
     void tStiffString_setDecayNoUpdate(tStiffString* const, Lfloat decay);
     void tStiffString_setDecayHighFreqNoUpdate(tStiffString* const, Lfloat decayHF);
 
+    //==============================================================================
+    /*!
+    @defgroup tshader tShaker
+    @ingroup physical
+    @brief PhISEM class - borrowed from STK
+    @{
+
+    @fn void    tShaker_init         (tShaker* const, Lfloat offset, Lfloat slope, LEAF* const leaf)
+    @brief Initialize a tShaker to the default mempool of a LEAF instance.
+    @param shaker A pointer to the tShaker to initialize.
+    @param leaf A pointer to the leaf instance.
+
+    @fn void    tShaker_initToPool   (tShaker* const, Lfloat offset, Lfloat slope, tMempool* const)
+    @brief Initialize a tShaker to a specified mempool.
+    @param shaker A pointer to the tShaker to initialize.
+    @param mempool A pointer to the tMempool to use.
+
+    @fn void    tShaker_free         (tShaker* const)
+    @brief Free a tShaker from its mempool.
+    @param shaker A pointer to the tShaker to free.
+
+    @fn Lfloat   tShaker_tick         (tShaker* const, Lfloat input)
+    @brief
+    @param shaker A pointer to the relevant tShaker.
+
+    @fn Lfloat   tShaker_excite        (tShaker* const, Lfloat energy)
+    @brief Excite the system with the given energy.
+    @param shaker A pointer to the relevant tShaker. 
+
+    @} */
+
+    typedef struct _tShaker
+    {
+        tMempool mempool;
+        Lfloat(*rand)(void);
+
+        tNoise noise;
+        tBiQuad resonator;
+
+        Lfloat energyDecay;
+        Lfloat soundDecay;
+        Lfloat probability;
+        Lfloat gain;
+
+        Lfloat energy;
+        Lfloat level;
+  
+    } _tShaker;
+
+    typedef _tShaker *tShaker;
 
+    void tShaker_init(tShaker *const, LEAF *const leaf);
+    void tShaker_initToPool(tShaker *const, tMempool *const);
+    void tShaker_free(tShaker *const);
+
+    Lfloat tShaker_tick(tShaker *const);
+    Lfloat tShaker_excite(tShaker *const, Lfloat energy);
+
+    void tShaker_setEnergyDecay(tShaker *const, Lfloat decay);
+    void tShaker_setSoundDecay(tShaker *const, Lfloat decay);
+    void tShaker_setProbability(tShaker *const, Lfloat prob);
+    void tShaker_setResonance (tShaker *const pm, Lfloat freq, Lfloat radius);
+
+    //==============================================================================
+    
 #ifdef __cplusplus
 }
 #endif
diff --git a/leaf/Src/leaf-physical.c b/leaf/Src/leaf-physical.c
index ac47cae..f1e097f 100644
--- a/leaf/Src/leaf-physical.c
+++ b/leaf/Src/leaf-physical.c
@@ -3985,3 +3985,96 @@ void tStiffString_pluckNoUpdate(tStiffString* const mp, Lfloat amp)
 }
 
 
+
+/// Shaker model
+
+void    tShaker_init(tShaker* const pm, LEAF* const leaf)
+{
+    tShaker_initToPool(pm, &leaf->mempool);
+}
+
+void    tShaker_initToPool(tShaker* const pm, tMempool* const mp)
+{
+    _tMempool* m = *mp;
+    _tShaker* p = *pm = (_tShaker*) mpool_alloc(sizeof(_tShaker), m);
+    p->mempool = m;
+
+    LEAF* leaf = p->mempool->leaf;
+    p->rand = leaf->random;
+
+    tBiQuad_initToPool(&p->resonator, mp);
+    tBiQuad_setResonance(&p->resonator, 4500., 0.99, false);
+    tNoise_initToPool(&p->noise, WhiteNoise, mp);
+
+    p->energy = 0.0;
+    p->level = 0.0;
+    p->energyDecay = 0.98;
+    p->soundDecay = 0.95;
+    p->probability = 0.10;
+}
+
+void    tShaker_free(tShaker* const pm)
+{
+    _tShaker* p = *pm;
+    
+    mpool_free((char*)p, p->mempool);
+}
+
+Lfloat   tShaker_tick(tShaker* const pm)
+{
+    _tShaker* p = *pm;
+
+    // exponential decay for system energy
+    p->energy *= p->energyDecay;
+
+    // stochastic particle collision event
+    if(p->rand() < p->probability)
+        p->level += p->energy * p->gain;
+
+    // exponential decay for sound
+    p->level *= p->soundDecay;
+
+    // add noise, filter
+    Lfloat sample    = p->level * tNoise_tick(&p->noise);
+    Lfloat output    = tBiQuad_tick(&p->resonator, sample);
+    
+    return output;
+}
+
+Lfloat     tShaker_excite   (tShaker* const pm, Lfloat energy)
+{ 
+    _tShaker* p = *pm;
+
+     // excite the system
+    p->energy += energy;
+    return p->energy;
+}
+
+void        tShaker_setEnergyDecay   (tShaker *const pm, Lfloat decay) 
+{
+    _tShaker* p = *pm;
+    p->energyDecay = decay;
+}
+
+void        tShaker_setSoundDecay   (tShaker *const pm, Lfloat decay) 
+{
+    _tShaker* p = *pm;
+    p->soundDecay = decay;
+}
+
+void        tShaker_setProbability (tShaker *const pm, Lfloat prob) 
+{
+    _tShaker* p = *pm;
+
+    // set gain correction for number of particles
+    float nBeans = 1024.0 * prob;
+    float gain = (log(nBeans)  / log(4.)) * (40/nBeans);
+
+    p->probability = prob;
+    p->gain = gain;
+}
+
+void        tShaker_setResonance (tShaker *const pm, Lfloat freq, Lfloat radius) {
+   _tShaker* p = *pm;
+    tBiQuad_setResonance(&p->resonator, freq, radius, false);
+}